diff --git a/src/tools/pginclude/pgrminclude b/src/tools/pginclude/pgrminclude
index 2ac9c78880f..d60519a0371 100755
--- a/src/tools/pginclude/pgrminclude
+++ b/src/tools/pginclude/pgrminclude
@@ -43,6 +43,8 @@ compile_file() {
 	[ "$INCLUDE" = "postgres_fe.h" ] && continue
 	[ "$INCLUDE" = "pg_config.h" ] && continue
 	[ "$INCLUDE" = "c.h" ] && continue
+	# CppAsString2 will expand undefined identifiers, so skip files that use it
+	grep -q '\<CppAsString2\>' "$FILE" && continue
 
 	# preserve configure-specific includes
 	# these includes are surrounded by #ifdef's