diff --git a/include/spdk/json.h b/include/spdk/json.h
index 42cb5e859..cd76c5e90 100644
--- a/include/spdk/json.h
+++ b/include/spdk/json.h
@@ -225,6 +225,8 @@ int spdk_json_write_string_utf16le_raw(struct spdk_json_write_ctx *w, const uint
 
 int spdk_json_write_string_fmt(struct spdk_json_write_ctx *w, const char *fmt,
 			       ...) __attribute__((__format__(__printf__, 2, 3)));
+int spdk_json_write_string_fmt_v(struct spdk_json_write_ctx *w, const char *fmt, va_list args);
+
 int spdk_json_write_array_begin(struct spdk_json_write_ctx *w);
 int spdk_json_write_array_end(struct spdk_json_write_ctx *w);
 int spdk_json_write_object_begin(struct spdk_json_write_ctx *w);
@@ -251,6 +253,9 @@ int spdk_json_write_named_int64(struct spdk_json_write_ctx *w, const char *name,
 int spdk_json_write_named_string(struct spdk_json_write_ctx *w, const char *name, const char *val);
 int spdk_json_write_named_string_fmt(struct spdk_json_write_ctx *w, const char *name,
 				     const char *fmt, ...) __attribute__((__format__(__printf__, 3, 4)));
+int spdk_json_write_named_string_fmt_v(struct spdk_json_write_ctx *w, const char *name,
+				       const char *fmt, va_list args);
+
 int spdk_json_write_named_array_begin(struct spdk_json_write_ctx *w, const char *name);
 int spdk_json_write_named_object_begin(struct spdk_json_write_ctx *w, const char *name);
 
diff --git a/lib/json/json_write.c b/lib/json/json_write.c
index d1058c54d..0cd600be8 100644
--- a/lib/json/json_write.c
+++ b/lib/json/json_write.c
@@ -431,14 +431,23 @@ spdk_json_write_string_utf16le(struct spdk_json_write_ctx *w, const uint16_t *va
 int
 spdk_json_write_string_fmt(struct spdk_json_write_ctx *w, const char *fmt, ...)
 {
-	char *s;
 	va_list args;
 	int rc;
 
 	va_start(args, fmt);
-	s = spdk_vsprintf_alloc(fmt, args);
+	rc = spdk_json_write_string_fmt_v(w, fmt, args);
 	va_end(args);
 
+	return rc;
+}
+
+int
+spdk_json_write_string_fmt_v(struct spdk_json_write_ctx *w, const char *fmt, va_list args)
+{
+	char *s;
+	int rc;
+
+	s = spdk_vsprintf_alloc(fmt, args);
 	if (s == NULL) {
 		return -1;
 	}
@@ -631,18 +640,28 @@ int spdk_json_write_named_string(struct spdk_json_write_ctx *w, const char *name
 int spdk_json_write_named_string_fmt(struct spdk_json_write_ctx *w, const char *name,
 				     const char *fmt, ...)
 {
-	char *s;
 	va_list args;
 	int rc;
 
+	va_start(args, fmt);
+	rc = spdk_json_write_named_string_fmt_v(w, name, fmt, args);
+	va_end(args);
+
+	return rc;
+}
+
+int spdk_json_write_named_string_fmt_v(struct spdk_json_write_ctx *w, const char *name,
+				       const char *fmt, va_list args)
+{
+	char *s;
+	int rc;
+
 	rc = spdk_json_write_name(w, name);
 	if (rc) {
 		return rc;
 	}
 
-	va_start(args, fmt);
 	s = spdk_vsprintf_alloc(fmt, args);
-	va_end(args);
 
 	if (s == NULL) {
 		return -1;