2 files changed, 3 insertions, 2 deletions
diff --git a/src/plugins/platforms/windows/qwindowsfontengine.cpp b/src/plugins/platforms/windows/qwindowsfontengine.cpp
index 86fcb666b0..79615e79ec 100644
--- a/src/plugins/platforms/windows/qwindowsfontengine.cpp
+++ b/src/plugins/platforms/windows/qwindowsfontengine.cpp
@@ -1032,6 +1032,7 @@ bool QWindowsFontEngine::getSfntTableData(uint tag, uchar *buffer, uint *length)
     SelectObject(hdc, hfont);
     DWORD t = qbswap<quint32>(tag);
     *length = GetFontData(hdc, t, 0, buffer, *length);
+    Q_ASSERT(*length == GDI_ERROR || int(*length) > 0);
     return *length != GDI_ERROR;
 }
 
diff --git a/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp b/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp
index 1c5e4508ac..158eee6b38 100644
--- a/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp
+++ b/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp
@@ -282,8 +282,8 @@ bool QWindowsFontEngineDirectWrite::getSfntTableData(uint tag, uchar *buffer, ui
             ret = true;
             if (buffer && *length >= tableSize)
                 memcpy(buffer, tableData, tableSize);
-            else
-                *length = tableSize;
+            *length = tableSize;
+            Q_ASSERT(int(*length) > 0);
         }
         m_directWriteFontFace->ReleaseFontTable(tableContext);
     } else {