diff --git a/Makefile b/Makefile
index 1fd74910..c26e6f24 100644
--- a/Makefile
+++ b/Makefile
@@ -78,6 +78,7 @@ CXXFLAGS    := \
               -std=c++11 \
               $(STATIC_FLAGS) \
               $(LTO_FLAGS) \
+              -Isrc \
               -Wall \
               -Wno-unused-result \
               -MMD
diff --git a/src/policy_cache.cpp b/src/policy_cache.cpp
index 7a0ef3f4..a62b0e4a 100644
--- a/src/policy_cache.cpp
+++ b/src/policy_cache.cpp
@@ -1 +1 @@
-#include "boost/unordered/unordered_flat_map.hpp"
+#include <boost/unordered/unordered_flat_map.hpp>