diff --git a/include/vcl/outdev.hxx b/include/vcl/outdev.hxx
index 8f5fd3832247..363cdbf62d90 100644
--- a/include/vcl/outdev.hxx
+++ b/include/vcl/outdev.hxx
@@ -1420,7 +1420,7 @@ public:
                                                   sal_Int32* pKashidaPosDropped // invalid kashida positions (out)
                                                 ) const;
 
-    sal_uInt16                  GetBitCount() const;
+    virtual sal_uInt16          GetBitCount() const;
 
     bool                        GetTextIsRTL( const OUString&, sal_Int32 nIndex, sal_Int32 nLen ) const;
 
@@ -1429,7 +1429,7 @@ public:
         @return 0, if no alpha channel available, and the bit depth of
         the alpha channel otherwise.
      */
-    sal_uInt16                  GetAlphaBitCount() const;
+    virtual sal_uInt16          GetAlphaBitCount() const;
     sal_uLong                   GetColorCount() const;
 
     void                        Push( sal_uInt16 nFlags = PUSH_ALL );
diff --git a/include/vcl/virdev.hxx b/include/vcl/virdev.hxx
index 5b25b72f6e6d..0436b5dc7161 100644
--- a/include/vcl/virdev.hxx
+++ b/include/vcl/virdev.hxx
@@ -134,8 +134,8 @@ public:
 
     void                SetReferenceDevice( sal_Int32 i_nDPIX, sal_Int32 i_nDPIY );
 
-    sal_uInt16          GetBitCount() const;
-    sal_uInt16          GetAlphaBitCount() const;
+    virtual sal_uInt16  GetBitCount() const SAL_OVERRIDE;
+    virtual sal_uInt16  GetAlphaBitCount() const SAL_OVERRIDE;
 
 private:
     SAL_DLLPRIVATE void ImplSetReferenceDevice( RefDevMode, sal_Int32 i_nDPIX, sal_Int32 i_nDPIY );