diff --git a/llvm/utils/TableGen/TGSourceMgr.h b/llvm/utils/TableGen/TGSourceMgr.h
index 9a61a9b009fc..33d3c1091527 100644
--- a/llvm/utils/TableGen/TGSourceMgr.h
+++ b/llvm/utils/TableGen/TGSourceMgr.h
@@ -14,6 +14,7 @@
 #ifndef TGSOURCEMGR_H
 #define TGSOURCEMGR_H
 
+#include <cassert>
 #include <vector>
 
 namespace llvm {