diff --git a/commit.h b/commit.h
index e5332efcfc..24128d7a2a 100644
--- a/commit.h
+++ b/commit.h
@@ -73,7 +73,6 @@ struct pretty_print_context
 	struct reflog_walk_info *reflog_info;
 };
 
-extern int non_ascii(int);
 extern int has_non_ascii(const char *text);
 struct rev_info; /* in revision.h, it circularly uses enum cmit_fmt */
 extern char *reencode_commit_message(const struct commit *commit,
diff --git a/pretty.c b/pretty.c
index 8f5bd1ab7f..9001379a9d 100644
--- a/pretty.c
+++ b/pretty.c
@@ -83,7 +83,7 @@ static int get_one_line(const char *msg)
 }
 
 /* High bit set, or ISO-2022-INT */
-int non_ascii(int ch)
+static int non_ascii(int ch)
 {
 	return !isascii(ch) || ch == '\033';
 }