diff --git a/library/bignum_core.c b/library/bignum_core.c
index fd59ba1e1..81a5acabf 100644
--- a/library/bignum_core.c
+++ b/library/bignum_core.c
@@ -35,21 +35,18 @@
 
 size_t mbedtls_mpi_core_clz(mbedtls_mpi_uint a)
 {
-
+    
 #if defined(__has_builtin)
-#if (MBEDTLS_MPI_UINT_MAX == UINT_MAX)
-#if __has_builtin(__builtin_clz)
-    return (size_t) __builtin_clz(a);
-#endif
-#elif (MBEDTLS_MPI_UINT_MAX == ULONG_MAX)
-#if __has_builtin(__builtin_clzl)
-    return (size_t) __builtin_clzl(a);
-#endif
-#elif (MBEDTLS_MPI_UINT_MAX == ULLONG_MAX)
-#if __has_builtin(__builtin_clzll)
-    return (size_t) __builtin_clzll(a);
+#if (MBEDTLS_MPI_UINT_MAX == UINT_MAX) && __has_builtin(__builtin_clz)
+    #define core_clz __builtin_clz
+#elif (MBEDTLS_MPI_UINT_MAX == ULONG_MAX) && __has_builtin(__builtin_clzl)
+    #define core_clz __builtin_clzl
+#elif (MBEDTLS_MPI_UINT_MAX == ULLONG_MAX) && __has_builtin(__builtin_clzll)
+    #define core_clz __builtin_clzll
 #endif
 #endif
+#if defined(core_clz)
+    return (size_t) core_clz(a);
 #else
     size_t j;
     mbedtls_mpi_uint mask = (mbedtls_mpi_uint) 1 << (biL - 1);