diff --git a/polly/lib/Transform/ScheduleOptimizer.cpp b/polly/lib/Transform/ScheduleOptimizer.cpp
index 5fd86a0dee89..daaada2e5570 100644
--- a/polly/lib/Transform/ScheduleOptimizer.cpp
+++ b/polly/lib/Transform/ScheduleOptimizer.cpp
@@ -65,7 +65,6 @@
 #include "isl/space.h"
 #include "isl/union_map.h"
 #include "isl/union_set.h"
-#include <ciso646>
 
 using namespace llvm;
 using namespace polly;