diff --git a/library/x509_create.c b/library/x509_create.c
index 88148a6..1877672 100644
--- a/library/x509_create.c
+++ b/library/x509_create.c
@@ -223,7 +223,7 @@
     }
 
     cur->val.p[0] = critical;
-    memcpy( cur->val.p + 1, val, val_len );
+    mbedtls_platform_memcpy( cur->val.p + 1, val, val_len );
 
     return( 0 );
 }
@@ -304,7 +304,7 @@
 
     len = size;
     (*p) -= len;
-    memcpy( *p, sig, len );
+    mbedtls_platform_memcpy( *p, sig, len );
 
     if( *p - start < 1 )
         return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );