diff --git a/src/gui/painting/qpdf.cpp b/src/gui/painting/qpdf.cpp
index 843551d51f3..cfa0a28fda8 100644
--- a/src/gui/painting/qpdf.cpp
+++ b/src/gui/painting/qpdf.cpp
@@ -1524,6 +1524,7 @@ bool QPdfEngine::begin(QPaintDevice *pdev)
 
     d->pages.clear();
     d->imageCache.clear();
+    d->alphaCache.clear();
 
     setActive(true);
     d->writeHeader();