diff --git a/contrib/coccinelle/strbuf.cocci b/contrib/coccinelle/strbuf.cocci
index d9ada69b43..0970d98ad7 100644
--- a/contrib/coccinelle/strbuf.cocci
+++ b/contrib/coccinelle/strbuf.cocci
@@ -15,7 +15,7 @@ constant fmt !~ "%";
 @@
 expression E;
 struct strbuf SB;
-format F =~ "s";
+format F =~ "^s$";
 @@
 - strbuf_addf(E, "%@F@", SB.buf);
 + strbuf_addbuf(E, &SB);
@@ -23,7 +23,7 @@ format F =~ "s";
 @@
 expression E;
 struct strbuf *SBP;
-format F =~ "s";
+format F =~ "^s$";
 @@
 - strbuf_addf(E, "%@F@", SBP->buf);
 + strbuf_addbuf(E, SBP);
@@ -44,7 +44,7 @@ struct strbuf *SBP;
 
 @@
 expression E1, E2;
-format F =~ "s";
+format F =~ "^s$";
 @@
 - strbuf_addf(E1, "%@F@", E2);
 + strbuf_addstr(E1, E2);