diff --git a/src/symbol.c b/src/symbol.c
index 66d875d55..3c9e545fd 100644
--- a/src/symbol.c
+++ b/src/symbol.c
@@ -6,7 +6,6 @@
 
 #include <string.h>
 #include <mruby.h>
-#include <mruby/khash.h>
 #include <mruby/string.h>
 #include <mruby/dump.h>
 #include <mruby/class.h>