diff --git a/pretty.c b/pretty.c
index e0646bbc5d..55d44f19cd 100644
--- a/pretty.c
+++ b/pretty.c
@@ -399,7 +399,6 @@ static void add_rfc2047(struct strbuf *sb, const char *line, size_t len,
 	int i;
 	int line_len = last_line_length(sb);
 
-	strbuf_grow(sb, len * 3 + strlen(encoding) + 100);
 	strbuf_addf(sb, "=?%s?q?", encoding);
 	line_len += strlen(encoding) + 5; /* 5 for =??q? */