diff --git a/programs/aes/crypt_and_hash.c b/programs/aes/crypt_and_hash.c
index 5024f4a6f..8433ef83e 100644
--- a/programs/aes/crypt_and_hash.c
+++ b/programs/aes/crypt_and_hash.c
@@ -82,7 +82,8 @@ static void mbedtls_zeroize( void *v, size_t n ) {
 
 int main( int argc, char *argv[] )
 {
-    int ret = 1, i, n;
+    int ret = 1, i;
+    unsigned n;
     int exit_code = MBEDTLS_EXIT_FAILURE;
     int mode;
     size_t keylen, ilen, olen;
diff --git a/programs/pkey/pk_decrypt.c b/programs/pkey/pk_decrypt.c
index 1d8c959a0..1876ef30d 100644
--- a/programs/pkey/pk_decrypt.c
+++ b/programs/pkey/pk_decrypt.c
@@ -62,7 +62,8 @@ int main( void )
 int main( int argc, char *argv[] )
 {
     FILE *f;
-    int ret = 1, c;
+    int ret = 1;
+    unsigned c;
     int exit_code = MBEDTLS_EXIT_FAILURE;
     size_t i, olen = 0;
     mbedtls_pk_context pk;
diff --git a/programs/pkey/rsa_decrypt.c b/programs/pkey/rsa_decrypt.c
index 0a252d2ad..bc37c7457 100644
--- a/programs/pkey/rsa_decrypt.c
+++ b/programs/pkey/rsa_decrypt.c
@@ -63,7 +63,7 @@ int main( int argc, char *argv[] )
     FILE *f;
     int ret = 1;
     int exit_code = MBEDTLS_EXIT_FAILURE;
-    int c;
+    unsigned c;
     size_t i;
     mbedtls_rsa_context rsa;
     mbedtls_mpi N, P, Q, D, E, DP, DQ, QP;
diff --git a/programs/pkey/rsa_verify.c b/programs/pkey/rsa_verify.c
index 6f88345f2..a7875009e 100644
--- a/programs/pkey/rsa_verify.c
+++ b/programs/pkey/rsa_verify.c
@@ -57,7 +57,8 @@ int main( void )
 int main( int argc, char *argv[] )
 {
     FILE *f;
-    int ret = 1, c;
+    int ret = 1;
+    unsigned c;
     int exit_code = MBEDTLS_EXIT_FAILURE;
     size_t i;
     mbedtls_rsa_context rsa;