diff --git a/src/base/trace.cc b/src/base/trace.cc
index 22e05e6..7783b6d 100644
--- a/src/base/trace.cc
+++ b/src/base/trace.cc
@@ -29,7 +29,7 @@
  *          Steve Reinhardt
  */
 
-#include <ctype.h>
+#include <cctype>
 #include <fstream>
 #include <iostream>
 #include <list>