diff --git a/dlls/gdi32/bitblt.c b/dlls/gdi32/bitblt.c
index abd4dfc7fe9..7167c4a1058 100644
--- a/dlls/gdi32/bitblt.c
+++ b/dlls/gdi32/bitblt.c
@@ -170,7 +170,9 @@ DWORD convert_bits( const BITMAPINFO *src_info, struct bitblt_coords *src,
     DWORD err;
 
     dst_info->bmiHeader.biWidth = src->visrect.right - src->visrect.left;
-    if (!(ptr = HeapAlloc( GetProcessHeap(), 0, get_dib_image_size( dst_info ))))
+    dst_info->bmiHeader.biSizeImage = get_dib_image_size( dst_info );
+
+    if (!(ptr = HeapAlloc( GetProcessHeap(), 0, dst_info->bmiHeader.biSizeImage )))
         return ERROR_OUTOFMEMORY;
 
     err = convert_bitmapinfo( src_info, bits->ptr, src, dst_info, ptr, add_alpha );
@@ -190,8 +192,10 @@ DWORD stretch_bits( const BITMAPINFO *src_info, struct bitblt_coords *src,
 
     dst_info->bmiHeader.biWidth = dst->visrect.right - dst->visrect.left;
     dst_info->bmiHeader.biHeight = dst->visrect.bottom - dst->visrect.top;
+    dst_info->bmiHeader.biSizeImage = get_dib_image_size( dst_info );
+
     if (src_info->bmiHeader.biHeight < 0) dst_info->bmiHeader.biHeight = -dst_info->bmiHeader.biHeight;
-    if (!(ptr = HeapAlloc( GetProcessHeap(), 0, get_dib_image_size( dst_info ))))
+    if (!(ptr = HeapAlloc( GetProcessHeap(), 0, dst_info->bmiHeader.biSizeImage )))
         return ERROR_OUTOFMEMORY;
 
     err = stretch_bitmapinfo( src_info, bits->ptr, src, dst_info, ptr, dst, mode );
@@ -208,7 +212,7 @@ static DWORD blend_bits( const BITMAPINFO *src_info, const struct gdi_image_bits
 {
     if (!dst_bits->is_copy)
     {
-        int size = get_dib_image_size( dst_info );
+        int size = dst_info->bmiHeader.biSizeImage;
         void *ptr = HeapAlloc( GetProcessHeap(), 0, size );
         if (!ptr) return ERROR_OUTOFMEMORY;
         memcpy( ptr, dst_bits->ptr, size );
@@ -446,11 +450,11 @@ BOOL nulldrv_GradientFill( PHYSDEV dev, TRIVERTEX *vert_array, ULONG nvert,
     info->bmiHeader.biClrImportant  = 0;
     info->bmiHeader.biWidth         = dst.visrect.right - dst.visrect.left;
     info->bmiHeader.biHeight        = dst.visrect.bottom - dst.visrect.top;
-    info->bmiHeader.biSizeImage     = 0;
+    info->bmiHeader.biSizeImage     = get_dib_image_size( info );
     dev = GET_DC_PHYSDEV( dc, pPutImage );
     err = dev->funcs->pPutImage( dev, 0, 0, info, NULL, NULL, NULL, 0 );
     if ((err && err != ERROR_BAD_FORMAT) ||
-        !(bits.ptr = HeapAlloc( GetProcessHeap(), HEAP_ZERO_MEMORY, get_dib_image_size( info ))))
+        !(bits.ptr = HeapAlloc( GetProcessHeap(), HEAP_ZERO_MEMORY, info->bmiHeader.biSizeImage )))
     {
         ret = FALSE;
         goto done;
diff --git a/dlls/gdi32/brush.c b/dlls/gdi32/brush.c
index 34d3a572be2..c86421c3289 100644
--- a/dlls/gdi32/brush.c
+++ b/dlls/gdi32/brush.c
@@ -126,12 +126,12 @@ static BOOL copy_bitmap( BRUSHOBJ *brush, HBITMAP bitmap )
         memcpy( &info->bmiHeader + 1, bmp->dib->dsBitfields, sizeof(bmp->dib->dsBitfields) );
     else if (info->bmiHeader.biClrUsed)
         memcpy( &info->bmiHeader + 1, bmp->color_table, info->bmiHeader.biClrUsed * sizeof(RGBQUAD) );
-    if (!(brush->bits.ptr = HeapAlloc( GetProcessHeap(), 0, get_dib_image_size( info ))))
+    if (!(brush->bits.ptr = HeapAlloc( GetProcessHeap(), 0, info->bmiHeader.biSizeImage )))
     {
         HeapFree( GetProcessHeap(), 0, info );
         goto done;
     }
-    memcpy( brush->bits.ptr, bmp->dib->dsBm.bmBits, get_dib_image_size( info ));
+    memcpy( brush->bits.ptr, bmp->dib->dsBm.bmBits, info->bmiHeader.biSizeImage );
     brush->bits.is_copy = TRUE;
     brush->bits.free = free_heap_bits;
     brush->info = info;