diff --git a/src/option.h b/src/option.h
index cf7ba04..60889ab 100644
--- a/src/option.h
+++ b/src/option.h
@@ -527,6 +527,9 @@
 EXTERN char_u	*p_header;	/* 'printheader' */
 #endif
 EXTERN int	p_prompt;	/* 'prompt' */
+#ifdef FEAT_TERMTRUECOLOR
+EXTERN int	p_guicolors;	/* 'guicolors' */
+#endif
 #ifdef FEAT_GUI
 EXTERN char_u	*p_guifont;	/* 'guifont' */
 # ifdef FEAT_XFONTSET