diff --git a/io.c b/io.c
index a6a7dd3f82..294abfe6b0 100644
--- a/io.c
+++ b/io.c
@@ -127,6 +127,7 @@
 #include "ccan/list/list.h"
 #include "internal/thread.h"
 #include "internal/transcode.h"
+#include "internal/variable.h"
 #include "ruby/io.h"
 #include "ruby/thread.h"
 #include "ruby/util.h"
diff --git a/ruby.c b/ruby.c
index 2d1a437e7d..509ba61352 100644
--- a/ruby.c
+++ b/ruby.c
@@ -56,6 +56,7 @@
 #include "internal/missing.h"
 #include "internal/object.h"
 #include "internal/parse.h"
+#include "internal/variable.h"
 #include "mjit.h"
 #include "ruby/encoding.h"
 #include "ruby/thread.h"