diff --git a/diff.c b/diff.c
index 4148ba6980..33c65f492d 100644
--- a/diff.c
+++ b/diff.c
@@ -5289,6 +5289,7 @@ static void show_rename_copy(struct diff_options *opt, const char *renamecopy,
 	emit_diff_symbol(opt, DIFF_SYMBOL_SUMMARY,
 				 sb.buf, sb.len, 0);
 	show_mode_change(opt, p, 0);
+	strbuf_release(&sb);
 }
 
 static void diff_summary(struct diff_options *opt, struct diff_filepair *p)