diff --git a/src/validators.cpp b/src/validators.cpp
index 0971890f6..1486d91f5 100644
--- a/src/validators.cpp
+++ b/src/validators.cpp
@@ -23,6 +23,7 @@
 #include <libaegisub/util.h>
 
 #include <wx/combobox.h>
+#include <wx/spinctrl.h>
 #include <wx/textctrl.h>
 
 namespace {