diff --git a/library/entropy.c b/library/entropy.c
index 8db3d94..2b1e7ef 100644
--- a/library/entropy.c
+++ b/library/entropy.c
@@ -462,9 +462,10 @@
     for( i = 0; i < ctx->source_count; i++ )
         ctx->source[i].size = 0;
 
-    mbedtls_platform_memcpy( output, buf, len );
-
-    ret = 0;
+    if( output == mbedtls_platform_memcpy( output, buf, len ) )
+    {
+        ret = 0;
+    }
 
 exit:
     mbedtls_platform_zeroize( buf, sizeof( buf ) );