diff --git a/src/qt/dc.cpp b/src/qt/dc.cpp
index 89f6c72811..a60a255ba1 100644
--- a/src/qt/dc.cpp
+++ b/src/qt/dc.cpp
@@ -82,14 +82,14 @@ bool wxQtDCImpl::CanGetTextExtent() const
 
 void wxQtDCImpl::DoGetSize(int *width, int *height) const
 {
-    *width  = m_qtPainter->device()->width();
-    *height = m_qtPainter->device()->height();
+    if (width)  *width  = m_qtPainter->device()->width();
+    if (height) *height = m_qtPainter->device()->height();
 }
 
 void wxQtDCImpl::DoGetSizeMM(int* width, int* height) const
 {
-    *width  = m_qtPainter->device()->widthMM();
-    *height = m_qtPainter->device()->heightMM();
+    if (width)  *width  = m_qtPainter->device()->widthMM();
+    if (height) *height = m_qtPainter->device()->heightMM();
 }
 
 int wxQtDCImpl::GetDepth() const
diff --git a/src/qt/window.cpp b/src/qt/window.cpp
index cc03c85c51..76c3ec29be 100644
--- a/src/qt/window.cpp
+++ b/src/qt/window.cpp
@@ -782,8 +782,8 @@ void wxWindowQt::DoGetSize(int *width, int *height) const
     wxASSERT( size.width() == rect.width() );
     wxASSERT( size.height() == rect.height() );
 
-    *width = rect.width();
-    *height = rect.height();
+    if (width)  *width = rect.width();
+    if (height) *height = rect.height();
 }
 
     
@@ -815,8 +815,8 @@ void wxWindowQt::DoSetSize(int x, int y, int width, int height, int sizeFlags )
 void wxWindowQt::DoGetClientSize(int *width, int *height) const
 {
     QRect geometry = GetHandle()->geometry();
-    *width = geometry.width();
-    *height = geometry.height();
+    if (width)  *width = geometry.width();
+    if (height) *height = geometry.height();
 }