diff --git a/src/common/imagtiff.cpp b/src/common/imagtiff.cpp
index 44a8fb3784..fb8a78a3a6 100644
--- a/src/common/imagtiff.cpp
+++ b/src/common/imagtiff.cpp
@@ -301,7 +301,7 @@ bool wxTIFFHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbos
 
     // guard against integer overflow during multiplication which could result
     // in allocating a too small buffer and then overflowing it
-    const double bytesNeeded = w * h * sizeof(uint32);
+    const double bytesNeeded = (double)w * (double)h * sizeof(uint32);
     if ( bytesNeeded >= 4294967295U /* UINT32_MAX */ )
     {
         if ( verbose )