diff --git a/src/corelib/tools/qvarlengtharray.h b/src/corelib/tools/qvarlengtharray.h
index 2d3c25a5dd5..8b9df7c12b6 100644
--- a/src/corelib/tools/qvarlengtharray.h
+++ b/src/corelib/tools/qvarlengtharray.h
@@ -350,6 +350,7 @@ Q_OUTOFLINE_TEMPLATE void QVarLengthArray<T, Prealloc>::realloc(int asize, int a
     int osize = s;
 
     const int copySize = qMin(asize, osize);
+    Q_ASSUME(copySize >= 0);
     if (aalloc != a) {
         if (aalloc > Prealloc) {
             T* newPtr = reinterpret_cast<T *>(malloc(aalloc * sizeof(T)));