diff --git a/check-return.txt b/check-return.txt
new file mode 100644
index 000000000..e6371ec69
--- /dev/null
+++ b/check-return.txt
@@ -0,0 +1,12 @@
+Bugfix
+   * Failures of alternative implementations of AES or DES single-block
+     functions enabled with MBEDTLS_AES_ENCRYPT_ALT, MBEDTLS_AES_DECRYPT_ALT,
+     MBEDTLS_DES_CRYPT_ECB_ALT or MBEDTLS_DES3_CRYPT_ECB_ALT were ignored.
+     This does not concern the implementation provided with Mbed TLS,
+     where this function cannot fail, or full-module replacements with
+     MBEDTLS_AES_ALT or MBEDTLS_DES_ALT. Reported by Armelle Duboc in #1092.
+
+Changes
+   * Warn if errors from AES or DES functions are ignored. This is currently
+     supported on GCC-like compilers and on MSVC and can be configured by
+     setting MBEDTLS_CHECK_RETURN in mbedtls_config.h.
diff --git a/include/mbedtls/aes.h b/include/mbedtls/aes.h
index 879c3f2a1..eb75935c1 100644
--- a/include/mbedtls/aes.h
+++ b/include/mbedtls/aes.h
@@ -163,6 +163,7 @@ void mbedtls_aes_xts_free( mbedtls_aes_xts_context *ctx );
  * \return         \c 0 on success.
  * \return         #MBEDTLS_ERR_AES_INVALID_KEY_LENGTH on failure.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_setkey_enc( mbedtls_aes_context *ctx, const unsigned char *key,
                     unsigned int keybits );
 
@@ -181,6 +182,7 @@ int mbedtls_aes_setkey_enc( mbedtls_aes_context *ctx, const unsigned char *key,
  * \return         \c 0 on success.
  * \return         #MBEDTLS_ERR_AES_INVALID_KEY_LENGTH on failure.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_setkey_dec( mbedtls_aes_context *ctx, const unsigned char *key,
                     unsigned int keybits );
 
@@ -201,6 +203,7 @@ int mbedtls_aes_setkey_dec( mbedtls_aes_context *ctx, const unsigned char *key,
  * \return         \c 0 on success.
  * \return         #MBEDTLS_ERR_AES_INVALID_KEY_LENGTH on failure.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_xts_setkey_enc( mbedtls_aes_xts_context *ctx,
                                 const unsigned char *key,
                                 unsigned int keybits );
@@ -221,6 +224,7 @@ int mbedtls_aes_xts_setkey_enc( mbedtls_aes_xts_context *ctx,
  * \return         \c 0 on success.
  * \return         #MBEDTLS_ERR_AES_INVALID_KEY_LENGTH on failure.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_xts_setkey_dec( mbedtls_aes_xts_context *ctx,
                                 const unsigned char *key,
                                 unsigned int keybits );
@@ -249,6 +253,7 @@ int mbedtls_aes_xts_setkey_dec( mbedtls_aes_xts_context *ctx,
 
  * \return         \c 0 on success.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_crypt_ecb( mbedtls_aes_context *ctx,
                     int mode,
                     const unsigned char input[16],
@@ -296,6 +301,7 @@ int mbedtls_aes_crypt_ecb( mbedtls_aes_context *ctx,
  * \return         #MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH
  *                 on failure.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_crypt_cbc( mbedtls_aes_context *ctx,
                     int mode,
                     size_t length,
@@ -340,6 +346,7 @@ int mbedtls_aes_crypt_cbc( mbedtls_aes_context *ctx,
  *                     smaller than an AES block in size (16 Bytes) or if \p
  *                     length is larger than 2^20 blocks (16 MiB).
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_crypt_xts( mbedtls_aes_xts_context *ctx,
                            int mode,
                            size_t length,
@@ -388,6 +395,7 @@ int mbedtls_aes_crypt_xts( mbedtls_aes_xts_context *ctx,
  *
  * \return         \c 0 on success.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_crypt_cfb128( mbedtls_aes_context *ctx,
                        int mode,
                        size_t length,
@@ -432,6 +440,7 @@ int mbedtls_aes_crypt_cfb128( mbedtls_aes_context *ctx,
  *
  * \return         \c 0 on success.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_crypt_cfb8( mbedtls_aes_context *ctx,
                     int mode,
                     size_t length,
@@ -486,6 +495,7 @@ int mbedtls_aes_crypt_cfb8( mbedtls_aes_context *ctx,
  *
  * \return         \c 0 on success.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_crypt_ofb( mbedtls_aes_context *ctx,
                        size_t length,
                        size_t *iv_off,
@@ -572,6 +582,7 @@ int mbedtls_aes_crypt_ofb( mbedtls_aes_context *ctx,
  *
  * \return                 \c 0 on success.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_crypt_ctr( mbedtls_aes_context *ctx,
                        size_t length,
                        size_t *nc_off,
@@ -592,6 +603,7 @@ int mbedtls_aes_crypt_ctr( mbedtls_aes_context *ctx,
  *
  * \return          \c 0 on success.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_internal_aes_encrypt( mbedtls_aes_context *ctx,
                                   const unsigned char input[16],
                                   unsigned char output[16] );
@@ -607,6 +619,7 @@ int mbedtls_internal_aes_encrypt( mbedtls_aes_context *ctx,
  *
  * \return          \c 0 on success.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_internal_aes_decrypt( mbedtls_aes_context *ctx,
                                   const unsigned char input[16],
                                   unsigned char output[16] );
@@ -618,6 +631,7 @@ int mbedtls_internal_aes_decrypt( mbedtls_aes_context *ctx,
  * \return         \c 0 on success.
  * \return         \c 1 on failure.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_self_test( int verbose );
 
 #endif /* MBEDTLS_SELF_TEST */
diff --git a/include/mbedtls/des.h b/include/mbedtls/des.h
index 63a8e00d1..7bd618c27 100644
--- a/include/mbedtls/des.h
+++ b/include/mbedtls/des.h
@@ -139,6 +139,7 @@ void mbedtls_des_key_set_parity( unsigned char key[MBEDTLS_DES_KEY_SIZE] );
  *                 security risk. We recommend considering stronger ciphers
  *                 instead.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des_key_check_key_parity( const unsigned char key[MBEDTLS_DES_KEY_SIZE] );
 
 /**
@@ -152,6 +153,7 @@ int mbedtls_des_key_check_key_parity( const unsigned char key[MBEDTLS_DES_KEY_SI
  *                 security risk. We recommend considering stronger ciphers
  *                 instead.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des_key_check_weak( const unsigned char key[MBEDTLS_DES_KEY_SIZE] );
 
 /**
@@ -166,6 +168,7 @@ int mbedtls_des_key_check_weak( const unsigned char key[MBEDTLS_DES_KEY_SIZE] );
  *                 security risk. We recommend considering stronger ciphers
  *                 instead.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des_setkey_enc( mbedtls_des_context *ctx, const unsigned char key[MBEDTLS_DES_KEY_SIZE] );
 
 /**
@@ -180,6 +183,7 @@ int mbedtls_des_setkey_enc( mbedtls_des_context *ctx, const unsigned char key[MB
  *                 security risk. We recommend considering stronger ciphers
  *                 instead.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des_setkey_dec( mbedtls_des_context *ctx, const unsigned char key[MBEDTLS_DES_KEY_SIZE] );
 
 /**
@@ -190,6 +194,7 @@ int mbedtls_des_setkey_dec( mbedtls_des_context *ctx, const unsigned char key[MB
  *
  * \return         0
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des3_set2key_enc( mbedtls_des3_context *ctx,
                       const unsigned char key[MBEDTLS_DES_KEY_SIZE * 2] );
 
@@ -201,6 +206,7 @@ int mbedtls_des3_set2key_enc( mbedtls_des3_context *ctx,
  *
  * \return         0
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des3_set2key_dec( mbedtls_des3_context *ctx,
                       const unsigned char key[MBEDTLS_DES_KEY_SIZE * 2] );
 
@@ -212,6 +218,7 @@ int mbedtls_des3_set2key_dec( mbedtls_des3_context *ctx,
  *
  * \return         0
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des3_set3key_enc( mbedtls_des3_context *ctx,
                       const unsigned char key[MBEDTLS_DES_KEY_SIZE * 3] );
 
@@ -223,6 +230,7 @@ int mbedtls_des3_set3key_enc( mbedtls_des3_context *ctx,
  *
  * \return         0
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des3_set3key_dec( mbedtls_des3_context *ctx,
                       const unsigned char key[MBEDTLS_DES_KEY_SIZE * 3] );
 
@@ -239,6 +247,7 @@ int mbedtls_des3_set3key_dec( mbedtls_des3_context *ctx,
  *                 security risk. We recommend considering stronger ciphers
  *                 instead.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des_crypt_ecb( mbedtls_des_context *ctx,
                     const unsigned char input[8],
                     unsigned char output[8] );
@@ -266,6 +275,7 @@ int mbedtls_des_crypt_ecb( mbedtls_des_context *ctx,
  *                 security risk. We recommend considering stronger ciphers
  *                 instead.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des_crypt_cbc( mbedtls_des_context *ctx,
                     int mode,
                     size_t length,
@@ -283,6 +293,7 @@ int mbedtls_des_crypt_cbc( mbedtls_des_context *ctx,
  *
  * \return         0 if successful
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des3_crypt_ecb( mbedtls_des3_context *ctx,
                      const unsigned char input[8],
                      unsigned char output[8] );
@@ -308,6 +319,7 @@ int mbedtls_des3_crypt_ecb( mbedtls_des3_context *ctx,
  *
  * \return         0 if successful, or MBEDTLS_ERR_DES_INVALID_INPUT_LENGTH
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des3_crypt_cbc( mbedtls_des3_context *ctx,
                      int mode,
                      size_t length,
@@ -338,6 +350,7 @@ void mbedtls_des_setkey( uint32_t SK[32],
  *
  * \return         0 if successful, or 1 if the test failed
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des_self_test( int verbose );
 
 #endif /* MBEDTLS_SELF_TEST */
diff --git a/library/aes.c b/library/aes.c
index 8e3358c49..4afc3c48a 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -1011,6 +1011,7 @@ int mbedtls_aes_crypt_cbc( mbedtls_aes_context *ctx,
                     unsigned char *output )
 {
     int i;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char temp[16];
 
     AES_VALIDATE_RET( ctx != NULL );
@@ -1040,7 +1041,9 @@ int mbedtls_aes_crypt_cbc( mbedtls_aes_context *ctx,
         while( length > 0 )
         {
             memcpy( temp, input, 16 );
-            mbedtls_aes_crypt_ecb( ctx, mode, input, output );
+            ret = mbedtls_aes_crypt_ecb( ctx, mode, input, output );
+            if( ret != 0 )
+                goto exit;
 
             for( i = 0; i < 16; i++ )
                 output[i] = (unsigned char)( output[i] ^ iv[i] );
@@ -1059,7 +1062,9 @@ int mbedtls_aes_crypt_cbc( mbedtls_aes_context *ctx,
             for( i = 0; i < 16; i++ )
                 output[i] = (unsigned char)( input[i] ^ iv[i] );
 
-            mbedtls_aes_crypt_ecb( ctx, mode, output, output );
+            ret = mbedtls_aes_crypt_ecb( ctx, mode, output, output );
+            if( ret != 0 )
+                goto exit;
             memcpy( iv, output, 16 );
 
             input  += 16;
@@ -1067,8 +1072,10 @@ int mbedtls_aes_crypt_cbc( mbedtls_aes_context *ctx,
             length -= 16;
         }
     }
+    ret = 0;
 
-    return( 0 );
+exit:
+    return( ret );
 }
 #endif /* MBEDTLS_CIPHER_MODE_CBC */
 
@@ -1222,6 +1229,7 @@ int mbedtls_aes_crypt_cfb128( mbedtls_aes_context *ctx,
                        unsigned char *output )
 {
     int c;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     size_t n;
 
     AES_VALIDATE_RET( ctx != NULL );
@@ -1242,7 +1250,11 @@ int mbedtls_aes_crypt_cfb128( mbedtls_aes_context *ctx,
         while( length-- )
         {
             if( n == 0 )
-                mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, iv, iv );
+            {
+                ret = mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, iv, iv );
+                if( ret != 0 )
+                    goto exit;
+            }
 
             c = *input++;
             *output++ = (unsigned char)( c ^ iv[n] );
@@ -1256,7 +1268,11 @@ int mbedtls_aes_crypt_cfb128( mbedtls_aes_context *ctx,
         while( length-- )
         {
             if( n == 0 )
-                mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, iv, iv );
+            {
+                ret = mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, iv, iv );
+                if( ret != 0 )
+                    goto exit;
+            }
 
             iv[n] = *output++ = (unsigned char)( iv[n] ^ *input++ );
 
@@ -1265,8 +1281,10 @@ int mbedtls_aes_crypt_cfb128( mbedtls_aes_context *ctx,
     }
 
     *iv_off = n;
+    ret = 0;
 
-    return( 0 );
+exit:
+    return( ret );
 }
 
 /*
@@ -1279,6 +1297,7 @@ int mbedtls_aes_crypt_cfb8( mbedtls_aes_context *ctx,
                             const unsigned char *input,
                             unsigned char *output )
 {
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char c;
     unsigned char ov[17];
 
@@ -1291,7 +1310,9 @@ int mbedtls_aes_crypt_cfb8( mbedtls_aes_context *ctx,
     while( length-- )
     {
         memcpy( ov, iv, 16 );
-        mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, iv, iv );
+        ret = mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, iv, iv );
+        if( ret != 0 )
+            goto exit;
 
         if( mode == MBEDTLS_AES_DECRYPT )
             ov[16] = *input;
@@ -1303,8 +1324,10 @@ int mbedtls_aes_crypt_cfb8( mbedtls_aes_context *ctx,
 
         memcpy( iv, ov + 1, 16 );
     }
+    ret = 0;
 
-    return( 0 );
+exit:
+    return( ret );
 }
 #endif /* MBEDTLS_CIPHER_MODE_CFB */
 
@@ -1366,6 +1389,7 @@ int mbedtls_aes_crypt_ctr( mbedtls_aes_context *ctx,
                        unsigned char *output )
 {
     int c, i;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     size_t n;
 
     AES_VALIDATE_RET( ctx != NULL );
@@ -1383,7 +1407,9 @@ int mbedtls_aes_crypt_ctr( mbedtls_aes_context *ctx,
     while( length-- )
     {
         if( n == 0 ) {
-            mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, nonce_counter, stream_block );
+            ret = mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, nonce_counter, stream_block );
+            if( ret != 0 )
+                goto exit;
 
             for( i = 16; i > 0; i-- )
                 if( ++nonce_counter[i - 1] != 0 )
@@ -1396,8 +1422,10 @@ int mbedtls_aes_crypt_ctr( mbedtls_aes_context *ctx,
     }
 
     *nc_off = n;
+    ret = 0;
 
-    return( 0 );
+exit:
+    return( ret );
 }
 #endif /* MBEDTLS_CIPHER_MODE_CTR */
 
diff --git a/library/des.c b/library/des.c
index 7f90faa04..91d22b5d9 100644
--- a/library/des.c
+++ b/library/des.c
@@ -28,6 +28,7 @@
 #if defined(MBEDTLS_DES_C)
 
 #include "mbedtls/des.h"
+#include "mbedtls/error.h"
 #include "mbedtls/platform_util.h"
 
 #include <string.h>
@@ -642,6 +643,7 @@ int mbedtls_des_crypt_cbc( mbedtls_des_context *ctx,
                     unsigned char *output )
 {
     int i;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char temp[8];
 
     if( length % 8 )
@@ -654,7 +656,9 @@ int mbedtls_des_crypt_cbc( mbedtls_des_context *ctx,
             for( i = 0; i < 8; i++ )
                 output[i] = (unsigned char)( input[i] ^ iv[i] );
 
-            mbedtls_des_crypt_ecb( ctx, output, output );
+            ret = mbedtls_des_crypt_ecb( ctx, output, output );
+            if( ret != 0 )
+                goto exit;
             memcpy( iv, output, 8 );
 
             input  += 8;
@@ -667,7 +671,9 @@ int mbedtls_des_crypt_cbc( mbedtls_des_context *ctx,
         while( length > 0 )
         {
             memcpy( temp, input, 8 );
-            mbedtls_des_crypt_ecb( ctx, input, output );
+            ret = mbedtls_des_crypt_ecb( ctx, input, output );
+            if( ret != 0 )
+                goto exit;
 
             for( i = 0; i < 8; i++ )
                 output[i] = (unsigned char)( output[i] ^ iv[i] );
@@ -679,8 +685,10 @@ int mbedtls_des_crypt_cbc( mbedtls_des_context *ctx,
             length -= 8;
         }
     }
+    ret = 0;
 
-    return( 0 );
+exit:
+    return( ret );
 }
 #endif /* MBEDTLS_CIPHER_MODE_CBC */
 
@@ -741,6 +749,7 @@ int mbedtls_des3_crypt_cbc( mbedtls_des3_context *ctx,
                      unsigned char *output )
 {
     int i;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char temp[8];
 
     if( length % 8 )
@@ -753,7 +762,9 @@ int mbedtls_des3_crypt_cbc( mbedtls_des3_context *ctx,
             for( i = 0; i < 8; i++ )
                 output[i] = (unsigned char)( input[i] ^ iv[i] );
 
-            mbedtls_des3_crypt_ecb( ctx, output, output );
+            ret = mbedtls_des3_crypt_ecb( ctx, output, output );
+            if( ret != 0 )
+                goto exit;
             memcpy( iv, output, 8 );
 
             input  += 8;
@@ -766,7 +777,9 @@ int mbedtls_des3_crypt_cbc( mbedtls_des3_context *ctx,
         while( length > 0 )
         {
             memcpy( temp, input, 8 );
-            mbedtls_des3_crypt_ecb( ctx, input, output );
+            ret = mbedtls_des3_crypt_ecb( ctx, input, output );
+            if( ret != 0 )
+                goto exit;
 
             for( i = 0; i < 8; i++ )
                 output[i] = (unsigned char)( output[i] ^ iv[i] );
@@ -778,8 +791,10 @@ int mbedtls_des3_crypt_cbc( mbedtls_des3_context *ctx,
             length -= 8;
         }
     }
+    ret = 0;
 
-    return( 0 );
+exit:
+    return( ret );
 }
 #endif /* MBEDTLS_CIPHER_MODE_CBC */
 
@@ -872,39 +887,43 @@ int mbedtls_des_self_test( int verbose )
         switch( i )
         {
         case 0:
-            mbedtls_des_setkey_dec( &ctx, des3_test_keys );
+            ret = mbedtls_des_setkey_dec( &ctx, des3_test_keys );
             break;
 
         case 1:
-            mbedtls_des_setkey_enc( &ctx, des3_test_keys );
+            ret = mbedtls_des_setkey_enc( &ctx, des3_test_keys );
             break;
 
         case 2:
-            mbedtls_des3_set2key_dec( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set2key_dec( &ctx3, des3_test_keys );
             break;
 
         case 3:
-            mbedtls_des3_set2key_enc( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set2key_enc( &ctx3, des3_test_keys );
             break;
 
         case 4:
-            mbedtls_des3_set3key_dec( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set3key_dec( &ctx3, des3_test_keys );
             break;
 
         case 5:
-            mbedtls_des3_set3key_enc( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set3key_enc( &ctx3, des3_test_keys );
             break;
 
         default:
             return( 1 );
         }
+        if( ret != 0 )
+            goto exit;
 
         for( j = 0; j < 100; j++ )
         {
             if( u == 0 )
-                mbedtls_des_crypt_ecb( &ctx, buf, buf );
+                ret = mbedtls_des_crypt_ecb( &ctx, buf, buf );
             else
-                mbedtls_des3_crypt_ecb( &ctx3, buf, buf );
+                ret = mbedtls_des3_crypt_ecb( &ctx3, buf, buf );
+            if( ret != 0 )
+                goto exit;
         }
 
         if( ( v == MBEDTLS_DES_DECRYPT &&
@@ -947,41 +966,45 @@ int mbedtls_des_self_test( int verbose )
         switch( i )
         {
         case 0:
-            mbedtls_des_setkey_dec( &ctx, des3_test_keys );
+            ret = mbedtls_des_setkey_dec( &ctx, des3_test_keys );
             break;
 
         case 1:
-            mbedtls_des_setkey_enc( &ctx, des3_test_keys );
+            ret = mbedtls_des_setkey_enc( &ctx, des3_test_keys );
             break;
 
         case 2:
-            mbedtls_des3_set2key_dec( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set2key_dec( &ctx3, des3_test_keys );
             break;
 
         case 3:
-            mbedtls_des3_set2key_enc( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set2key_enc( &ctx3, des3_test_keys );
             break;
 
         case 4:
-            mbedtls_des3_set3key_dec( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set3key_dec( &ctx3, des3_test_keys );
             break;
 
         case 5:
-            mbedtls_des3_set3key_enc( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set3key_enc( &ctx3, des3_test_keys );
             break;
 
         default:
             return( 1 );
         }
+        if( ret != 0 )
+            goto exit;
 
         if( v == MBEDTLS_DES_DECRYPT )
         {
             for( j = 0; j < 100; j++ )
             {
                 if( u == 0 )
-                    mbedtls_des_crypt_cbc( &ctx, v, 8, iv, buf, buf );
+                    ret = mbedtls_des_crypt_cbc( &ctx, v, 8, iv, buf, buf );
                 else
-                    mbedtls_des3_crypt_cbc( &ctx3, v, 8, iv, buf, buf );
+                    ret = mbedtls_des3_crypt_cbc( &ctx3, v, 8, iv, buf, buf );
+                if( ret != 0 )
+                    goto exit;
             }
         }
         else
@@ -991,9 +1014,11 @@ int mbedtls_des_self_test( int verbose )
                 unsigned char tmp[8];
 
                 if( u == 0 )
-                    mbedtls_des_crypt_cbc( &ctx, v, 8, iv, buf, buf );
+                    ret = mbedtls_des_crypt_cbc( &ctx, v, 8, iv, buf, buf );
                 else
-                    mbedtls_des3_crypt_cbc( &ctx3, v, 8, iv, buf, buf );
+                    ret = mbedtls_des3_crypt_cbc( &ctx3, v, 8, iv, buf, buf );
+                if( ret != 0 )
+                    goto exit;
 
                 memcpy( tmp, prv, 8 );
                 memcpy( prv, buf, 8 );
@@ -1027,6 +1052,8 @@ exit:
     mbedtls_des_free( &ctx );
     mbedtls_des3_free( &ctx3 );
 
+    if( ret != 0 )
+        ret = 1;
     return( ret );
 }
 
diff --git a/programs/pkey/dh_client.c b/programs/pkey/dh_client.c
index eccb42ad8..d633e4d1b 100644
--- a/programs/pkey/dh_client.c
+++ b/programs/pkey/dh_client.c
@@ -270,7 +270,9 @@ int main( void )
     mbedtls_printf( "...\n  . Receiving and decrypting the ciphertext" );
     fflush( stdout );
 
-    mbedtls_aes_setkey_dec( &aes, buf, 256 );
+    ret = mbedtls_aes_setkey_dec( &aes, buf, 256 );
+    if( ret != 0 )
+        goto exit;
 
     memset( buf, 0, sizeof( buf ) );
 
@@ -280,7 +282,9 @@ int main( void )
         goto exit;
     }
 
-    mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_DECRYPT, buf, buf );
+    ret = mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_DECRYPT, buf, buf );
+    if( ret != 0 )
+        goto exit;
     buf[16] = '\0';
     mbedtls_printf( "\n  . Plaintext is \"%s\"\n\n", (char *) buf );
 
diff --git a/programs/pkey/dh_server.c b/programs/pkey/dh_server.c
index 0ddb85cf8..75713ff58 100644
--- a/programs/pkey/dh_server.c
+++ b/programs/pkey/dh_server.c
@@ -290,9 +290,13 @@ int main( void )
     mbedtls_printf( "...\n  . Encrypting and sending the ciphertext" );
     fflush( stdout );
 
-    mbedtls_aes_setkey_enc( &aes, buf, 256 );
+    ret = mbedtls_aes_setkey_enc( &aes, buf, 256 );
+    if( ret != 0 )
+        goto exit;
     memcpy( buf, PLAINTEXT, 16 );
-    mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_ENCRYPT, buf, buf );
+    ret = mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_ENCRYPT, buf, buf );
+    if( ret != 0 )
+        goto exit;
 
     if( ( ret = mbedtls_net_send( &client_fd, buf, 16 ) ) != 16 )
     {
diff --git a/programs/test/benchmark.c b/programs/test/benchmark.c
index 5985caf0b..d3faad91e 100644
--- a/programs/test/benchmark.c
+++ b/programs/test/benchmark.c
@@ -674,7 +674,8 @@ int main( int argc, char *argv[] )
     {
         mbedtls_des3_context des3;
         mbedtls_des3_init( &des3 );
-        mbedtls_des3_set3key_enc( &des3, tmp );
+        if( mbedtls_des3_set3key_enc( &des3, tmp ) != 0 )
+            mbedtls_exit( 1 );
         TIME_AND_TSC( "3DES",
                 mbedtls_des3_crypt_cbc( &des3, MBEDTLS_DES_ENCRYPT, BUFSIZE, tmp, buf, buf ) );
         mbedtls_des3_free( &des3 );
@@ -684,7 +685,8 @@ int main( int argc, char *argv[] )
     {
         mbedtls_des_context des;
         mbedtls_des_init( &des );
-        mbedtls_des_setkey_enc( &des, tmp );
+        if( mbedtls_des_setkey_enc( &des, tmp ) != 0 )
+            mbedtls_exit( 1 );
         TIME_AND_TSC( "DES",
                 mbedtls_des_crypt_cbc( &des, MBEDTLS_DES_ENCRYPT, BUFSIZE, tmp, buf, buf ) );
         mbedtls_des_free( &des );
@@ -722,7 +724,7 @@ int main( int argc, char *argv[] )
 
             memset( buf, 0, sizeof( buf ) );
             memset( tmp, 0, sizeof( tmp ) );
-            mbedtls_aes_setkey_enc( &aes, tmp, keysize );
+            CHECK_AND_CONTINUE( mbedtls_aes_setkey_enc( &aes, tmp, keysize ) );
 
             TIME_AND_TSC( title,
                 mbedtls_aes_crypt_cbc( &aes, MBEDTLS_AES_ENCRYPT, BUFSIZE, tmp, buf, buf ) );
@@ -743,7 +745,7 @@ int main( int argc, char *argv[] )
 
             memset( buf, 0, sizeof( buf ) );
             memset( tmp, 0, sizeof( tmp ) );
-            mbedtls_aes_xts_setkey_enc( &ctx, tmp, keysize * 2 );
+            CHECK_AND_CONTINUE( mbedtls_aes_xts_setkey_enc( &ctx, tmp, keysize * 2 ) );
 
             TIME_AND_TSC( title,
                     mbedtls_aes_crypt_xts( &ctx, MBEDTLS_AES_ENCRYPT, BUFSIZE,
diff --git a/tests/suites/test_suite_aes.function b/tests/suites/test_suite_aes.function
index 1892c2595..52af8e02f 100644
--- a/tests/suites/test_suite_aes.function
+++ b/tests/suites/test_suite_aes.function
@@ -67,7 +67,7 @@ void aes_encrypt_cbc( data_t * key_str, data_t * iv_str,
 
     mbedtls_aes_init( &ctx );
 
-    mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 );
+    TEST_ASSERT( mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 ) == 0 );
     TEST_ASSERT( mbedtls_aes_crypt_cbc( &ctx, MBEDTLS_AES_ENCRYPT, src_str->len, iv_str->x, src_str->x, output ) == cbc_result );
     if( cbc_result == 0 )
     {
@@ -92,7 +92,7 @@ void aes_decrypt_cbc( data_t * key_str, data_t * iv_str,
     memset(output, 0x00, 100);
     mbedtls_aes_init( &ctx );
 
-    mbedtls_aes_setkey_dec( &ctx, key_str->x, key_str->len * 8 );
+    TEST_ASSERT( mbedtls_aes_setkey_dec( &ctx, key_str->x, key_str->len * 8 ) == 0 );
     TEST_ASSERT( mbedtls_aes_crypt_cbc( &ctx, MBEDTLS_AES_DECRYPT, src_str->len, iv_str->x, src_str->x, output ) == cbc_result );
     if( cbc_result == 0)
     {
@@ -241,7 +241,7 @@ void aes_encrypt_cfb128( data_t * key_str, data_t * iv_str,
     mbedtls_aes_init( &ctx );
 
 
-    mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 );
+    TEST_ASSERT( mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 ) == 0 );
     TEST_ASSERT( mbedtls_aes_crypt_cfb128( &ctx, MBEDTLS_AES_ENCRYPT, 16, &iv_offset, iv_str->x, src_str->x, output ) == 0 );
 
     TEST_ASSERT( mbedtls_test_hexcmp( output, dst->x, 16, dst->len ) == 0 );
@@ -263,7 +263,7 @@ void aes_decrypt_cfb128( data_t * key_str, data_t * iv_str,
     mbedtls_aes_init( &ctx );
 
 
-    mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 );
+    TEST_ASSERT( mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 ) == 0 );
     TEST_ASSERT( mbedtls_aes_crypt_cfb128( &ctx, MBEDTLS_AES_DECRYPT, 16, &iv_offset, iv_str->x, src_str->x, output ) == 0 );
 
     TEST_ASSERT( mbedtls_test_hexcmp( output, dst->x, 16, dst->len ) == 0 );
@@ -284,7 +284,7 @@ void aes_encrypt_cfb8( data_t * key_str, data_t * iv_str,
     mbedtls_aes_init( &ctx );
 
 
-    mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 );
+    TEST_ASSERT( mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 ) == 0 );
     TEST_ASSERT( mbedtls_aes_crypt_cfb8( &ctx, MBEDTLS_AES_ENCRYPT, src_str->len, iv_str->x, src_str->x, output ) == 0 );
 
     TEST_ASSERT( mbedtls_test_hexcmp( output, dst->x,
@@ -306,7 +306,7 @@ void aes_decrypt_cfb8( data_t * key_str, data_t * iv_str,
     mbedtls_aes_init( &ctx );
 
 
-    mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 );
+    TEST_ASSERT( mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 ) == 0 );
     TEST_ASSERT( mbedtls_aes_crypt_cfb8( &ctx, MBEDTLS_AES_DECRYPT, src_str->len, iv_str->x, src_str->x, output ) == 0 );
 
     TEST_ASSERT( mbedtls_test_hexcmp( output, dst->x,
diff --git a/tests/suites/test_suite_des.function b/tests/suites/test_suite_des.function
index 5b249355b..7256fb537 100644
--- a/tests/suites/test_suite_des.function
+++ b/tests/suites/test_suite_des.function
@@ -24,7 +24,7 @@ void des_encrypt_ecb( data_t * key_str, data_t * src_str, data_t * dst )
     mbedtls_des_init( &ctx );
 
 
-    mbedtls_des_setkey_enc( &ctx, key_str->x );
+    TEST_ASSERT( mbedtls_des_setkey_enc( &ctx, key_str->x ) == 0 );
     TEST_ASSERT( mbedtls_des_crypt_ecb( &ctx, src_str->x, output ) == 0 );
 
     TEST_ASSERT( mbedtls_test_hexcmp( output, dst->x, 8, dst->len ) == 0 );
@@ -44,7 +44,7 @@ void des_decrypt_ecb( data_t * key_str, data_t * src_str, data_t * dst )
     mbedtls_des_init( &ctx );
 
 
-    mbedtls_des_setkey_dec( &ctx, key_str->x );
+    TEST_ASSERT( mbedtls_des_setkey_dec( &ctx, key_str->x ) == 0 );
     TEST_ASSERT( mbedtls_des_crypt_ecb( &ctx, src_str->x, output ) == 0 );
 
     TEST_ASSERT( mbedtls_test_hexcmp( output, dst->x, 8, dst->len ) == 0 );
@@ -65,7 +65,7 @@ void des_encrypt_cbc( data_t * key_str, data_t * iv_str,
     mbedtls_des_init( &ctx );
 
 
-    mbedtls_des_setkey_enc( &ctx, key_str->x );
+    TEST_ASSERT( mbedtls_des_setkey_enc( &ctx, key_str->x ) == 0 );
     TEST_ASSERT( mbedtls_des_crypt_cbc( &ctx, MBEDTLS_DES_ENCRYPT, src_str->len, iv_str->x, src_str->x, output ) == cbc_result );
     if( cbc_result == 0 )
     {
@@ -91,7 +91,7 @@ void des_decrypt_cbc( data_t * key_str, data_t * iv_str,
     mbedtls_des_init( &ctx );
 
 
-    mbedtls_des_setkey_dec( &ctx, key_str->x );
+    TEST_ASSERT( mbedtls_des_setkey_dec( &ctx, key_str->x ) == 0 );
     TEST_ASSERT( mbedtls_des_crypt_cbc( &ctx, MBEDTLS_DES_DECRYPT, src_str->len, iv_str->x, src_str->x, output ) == cbc_result );
     if( cbc_result == 0 )
     {
@@ -117,9 +117,9 @@ void des3_encrypt_ecb( int key_count, data_t * key_str,
 
 
     if( key_count == 2 )
-        mbedtls_des3_set2key_enc( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set2key_enc( &ctx, key_str->x ) == 0 );
     else if( key_count == 3 )
-        mbedtls_des3_set3key_enc( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set3key_enc( &ctx, key_str->x ) == 0 );
     else
         TEST_ASSERT( 0 );
 
@@ -144,9 +144,9 @@ void des3_decrypt_ecb( int key_count, data_t * key_str,
 
 
     if( key_count == 2 )
-        mbedtls_des3_set2key_dec( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set2key_dec( &ctx, key_str->x ) == 0 );
     else if( key_count == 3 )
-        mbedtls_des3_set3key_dec( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set3key_dec( &ctx, key_str->x ) == 0 );
     else
         TEST_ASSERT( 0 );
 
@@ -172,9 +172,9 @@ void des3_encrypt_cbc( int key_count, data_t * key_str,
 
 
     if( key_count == 2 )
-        mbedtls_des3_set2key_enc( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set2key_enc( &ctx, key_str->x ) == 0 );
     else if( key_count == 3 )
-        mbedtls_des3_set3key_enc( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set3key_enc( &ctx, key_str->x ) == 0 );
     else
         TEST_ASSERT( 0 );
 
@@ -205,9 +205,9 @@ void des3_decrypt_cbc( int key_count, data_t * key_str,
 
 
     if( key_count == 2 )
-        mbedtls_des3_set2key_dec( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set2key_dec( &ctx, key_str->x ) == 0 );
     else if( key_count == 3 )
-        mbedtls_des3_set3key_dec( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set3key_dec( &ctx, key_str->x ) == 0 );
     else
         TEST_ASSERT( 0 );