diff --git a/dlls/comctl32/imagelist.c b/dlls/comctl32/imagelist.c
index 70457c78f53..71145ed791f 100644
--- a/dlls/comctl32/imagelist.c
+++ b/dlls/comctl32/imagelist.c
@@ -296,7 +296,7 @@ static BOOL add_with_alpha( HIMAGELIST himl, HDC hdc, int pos, int count,
         mask_info->bmiHeader = info->bmiHeader;
         mask_info->bmiHeader.biBitCount = 1;
         mask_info->bmiHeader.biSizeImage = mask_width * height;
-        if (!(mask_bits = HeapAlloc( GetProcessHeap(), HEAP_ZERO_MEMORY, info->bmiHeader.biSizeImage )))
+        if (!(mask_bits = HeapAlloc( GetProcessHeap(), HEAP_ZERO_MEMORY, mask_info->bmiHeader.biSizeImage )))
             goto done;
         if (!GetDIBits( hdc, hbmMask, 0, height, mask_bits, mask_info, DIB_RGB_COLORS )) goto done;
     }