diff --git a/experimental/SkSetPoly3To3.cpp b/experimental/SkSetPoly3To3.cpp
index 4a6cf7d..d27e7b1 100644
--- a/experimental/SkSetPoly3To3.cpp
+++ b/experimental/SkSetPoly3To3.cpp
@@ -7,6 +7,9 @@
  */
 #include "SkMatrix.h"
 
+// FIXME: needs to be in a header
+bool SkSetPoly3To3(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]);
+
 static void computeOuterProduct(SkScalar op[4],
                                 const SkPoint pts0[3], const SkPoint& ave0,
                                 const SkPoint pts1[3], const SkPoint& ave1) {