diff --git a/tests/PictureTest.cpp b/tests/PictureTest.cpp
index e50f74e..207e610 100644
--- a/tests/PictureTest.cpp
+++ b/tests/PictureTest.cpp
@@ -35,7 +35,7 @@
     }
 }
 
-void make_checkerboard(SkBitmap* bm, int w, int h, bool immutable) {
+static void make_checkerboard(SkBitmap* bm, int w, int h, bool immutable) {
     SkASSERT(w % 2 == 0);
     SkASSERT(h % 2 == 0);
     bm->setConfig(SkBitmap::kA8_Config, w, h);