diff --git a/core/include/blue/core/stringstream.h b/core/include/blue/core/stringstream.h
index 7d46590..86ef69a 100644
--- a/core/include/blue/core/stringstream.h
+++ b/core/include/blue/core/stringstream.h
@@ -28,6 +28,8 @@ BLUE_API void b_stringstream_pop_indent(b_stringstream *strv);
 BLUE_API b_status b_stringstream_add(b_stringstream *strv, const char *str);
 BLUE_API b_status b_stringstream_addf(b_stringstream *strv, const char *format, ...);
 BLUE_API b_status b_stringstream_addv(b_stringstream *strv, const char **strs);
+BLUE_API b_status b_stringstream_addvf(
+	b_stringstream *strv, const char *format, va_list arg);
 BLUE_API b_status b_stringstream_addvl(
 	b_stringstream *strv, const char **strs, size_t count);
 BLUE_API b_status b_stringstream_add_many(b_stringstream *strv, ...);
diff --git a/core/stringstream.c b/core/stringstream.c
index 83c9660..5542921 100644
--- a/core/stringstream.c
+++ b/core/stringstream.c
@@ -150,9 +150,18 @@ b_status b_stringstream_addf(struct b_stringstream *ss, const char *format, ...)
 	char str[1024];
 	va_list arg;
 	va_start(arg, format);
-	size_t len = vsnprintf(str, sizeof str, format, arg);
+	enum b_status status = b_stringstream_addvf(ss, format, arg);
 	va_end(arg);
 
+	return status;
+}
+
+b_status b_stringstream_addvf(
+	struct b_stringstream *ss, const char *format, va_list arg)
+{
+	char str[1024];
+	size_t len = vsnprintf(str, sizeof str, format, arg);
+
 	return ss_builder_push_string(ss, str, len);
 }