diff --git a/passes/techmap/abc.cc b/passes/techmap/abc.cc
index 5b19d84fb..bf05c68e7 100644
--- a/passes/techmap/abc.cc
+++ b/passes/techmap/abc.cc
@@ -49,6 +49,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <cctype>
 #include <cerrno>
 #include <sstream>
 #include <climits>