diff --git a/utils/TableGen/TGSourceMgr.h b/utils/TableGen/TGSourceMgr.h
index 9a61a9b009f..33d3c109152 100644
--- a/utils/TableGen/TGSourceMgr.h
+++ b/utils/TableGen/TGSourceMgr.h
@@ -14,6 +14,7 @@
 #ifndef TGSOURCEMGR_H
 #define TGSOURCEMGR_H
 
+#include <cassert>
 #include <vector>
 
 namespace llvm {