diff --git a/docs/technical/strbuf.txt b/docs/technical/strbuf.txt
index 49fa956..0e70ece 100644
--- a/docs/technical/strbuf.txt
+++ b/docs/technical/strbuf.txt
@@ -59,7 +59,7 @@ va_end(va);
 if (len > 0) {
     strbuf_expand(s, len);
     va_start(va, fmt);
-    len = strbuf_append_va(s, fmt, va);
+    strbuf_append_va(s, fmt, va);
     va_end(va);
 }
 ----
diff --git a/src/strbuf.c b/src/strbuf.c
index baeb86b..97427d8 100644
--- a/src/strbuf.c
+++ b/src/strbuf.c
@@ -133,7 +133,7 @@ void strbuf_appendf(strbuf_t *s, const char *fmt, ...) {
     if (len > 0) {
         strbuf_expand(s, len);
         va_start(va, fmt);
-        len = strbuf_append_va(s, fmt, va);
+        strbuf_append_va(s, fmt, va);
         va_end(va);
     }
 }