diff --git a/include/llvm/Support/Casting.h b/include/llvm/Support/Casting.h
index 5132b4ec288..6630fa955d3 100644
--- a/include/llvm/Support/Casting.h
+++ b/include/llvm/Support/Casting.h
@@ -15,6 +15,8 @@
 #ifndef LLVM_SUPPORT_CASTING_H
 #define LLVM_SUPPORT_CASTING_H
 
+#include <cassert>
+
 namespace llvm {
 
 //===----------------------------------------------------------------------===//