diff --git a/src/FileNames.h b/src/FileNames.h
index 620d74abc..44d2ea22c 100644
--- a/src/FileNames.h
+++ b/src/FileNames.h
@@ -21,6 +21,7 @@
 
 class wxFileName;
 class wxFileNameWrapper;
+class wxFrame;
 
 namespace FileNames
 {