diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 415dab8..a954d86 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -3760,7 +3760,7 @@
      * Even if the operation succeeds, make sure we clear the rest of the
      * buffer to prevent potential leakage of anything previously placed in
      * the same buffer.*/
-    if( tag )
+    if( tag != NULL )
     {
         if( status != PSA_SUCCESS )
             memset( tag, '!', tag_size );