diff --git a/paddle/math/MathFunctions.h b/paddle/math/MathFunctions.h
index 9297ae78c27aaf093a35429740a29199c1d09015..e8ea6e37ac527a19c529d1731b94bed970211755 100644
--- a/paddle/math/MathFunctions.h
+++ b/paddle/math/MathFunctions.h
@@ -106,6 +106,7 @@ T dotProduct(const int n, const T* x, const T* y) {
   for (int i = 0; i < n; i++) {
     result += x[i] * y[i];
   }
+  return result;
 }
 
 template <class T>