diff --git a/tinyxml2.h b/tinyxml2.h
index 8d5eb2a..fbfe4f6 100755
--- a/tinyxml2.h
+++ b/tinyxml2.h
@@ -570,6 +570,9 @@
         if ( p == q ) {
             return true;
         }
+        TIXMLASSERT( p );
+        TIXMLASSERT( q );
+        TIXMLASSERT( nChar >= 0 );
         return strncmp( p, q, nChar ) == 0;
     }