1 files changed, 1 insertions, 0 deletions
diff --git a/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp b/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp
index 158eee6b38..a4e4dd38d4 100644
--- a/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp
+++ b/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp
@@ -318,6 +318,7 @@ inline unsigned int getChar(const QChar *str, int &i, const int len)
 bool QWindowsFontEngineDirectWrite::stringToCMap(const QChar *str, int len, QGlyphLayout *glyphs,
                                                  int *nglyphs, QFontEngine::ShaperFlags flags) const
 {
+    Q_ASSERT(glyphs->numGlyphs >= *nglyphs);
     if (*nglyphs < len) {
         *nglyphs = len;
         return false;