diff --git a/gtsam/hybrid/tests/testHybridBayesNet.cpp b/gtsam/hybrid/tests/testHybridBayesNet.cpp
index 127160ab6..5f54c57b6 100644
--- a/gtsam/hybrid/tests/testHybridBayesNet.cpp
+++ b/gtsam/hybrid/tests/testHybridBayesNet.cpp
@@ -34,6 +34,7 @@
 #include <CppUnitLite/TestHarness.h>
 
 #include <memory>
+#include <numeric>
 
 using namespace std;
 using namespace gtsam;