diff --git a/src/option.h b/src/option.h
index 75c83d5..89cec94 100644
--- a/src/option.h
+++ b/src/option.h
@@ -622,6 +622,9 @@
 EXTERN char_u	*p_guifontwide;	// 'guifontwide'
 EXTERN int	p_guipty;	// 'guipty'
 #endif
+#ifdef FEAT_GUI_GTK
+EXTERN char_u	*p_guiligatures;  // 'guiligatures'
+# endif
 #if defined(FEAT_GUI_GTK) || defined(FEAT_GUI_X11)
 EXTERN long	p_ghr;		// 'guiheadroom'
 #endif