diff --git a/src/effects/SkLayerRasterizer.cpp b/src/effects/SkLayerRasterizer.cpp
index ad16ea8..5aa883d 100644
--- a/src/effects/SkLayerRasterizer.cpp
+++ b/src/effects/SkLayerRasterizer.cpp
@@ -108,8 +108,12 @@
     {
         mask->fFormat   = SkMask::kA8_Format;
         mask->fRowBytes = mask->fBounds.width();
-        mask->fImage = SkMask::AllocImage(mask->computeImageSize());
-        memset(mask->fImage, 0, mask->computeImageSize());
+        size_t size = mask->computeImageSize();
+        if (0 == size) {
+            return false;   // too big to allocate, abort
+        }
+        mask->fImage = SkMask::AllocImage(size);
+        memset(mask->fImage, 0, size);
     }
 
     if (SkMask::kJustComputeBounds_CreateMode != mode)