diff --git a/common/json.c b/common/json.c
index 8cd37cdd0..af99b2e82 100644
--- a/common/json.c
+++ b/common/json.c
@@ -105,6 +105,21 @@ bool json_to_u16(const char *buffer, const jsmntok_t *tok,
 	return true;
 }
 
+bool json_to_u32(const char *buffer, const jsmntok_t *tok,
+		 uint32_t *num)
+{
+	uint64_t u64;
+
+	if (!json_to_u64(buffer, tok, &u64))
+		return false;
+	*num = u64;
+
+	/* Just in case it doesn't fit. */
+	if (*num != u64)
+		return false;
+	return true;
+}
+
 bool json_to_int(const char *buffer, const jsmntok_t *tok, int *num)
 {
 	char *end;
diff --git a/common/json.h b/common/json.h
index 355af0103..80548671a 100644
--- a/common/json.h
+++ b/common/json.h
@@ -37,6 +37,10 @@ bool json_to_number(const char *buffer, const jsmntok_t *tok,
 bool json_to_u64(const char *buffer, const jsmntok_t *tok,
 		 uint64_t *num);
 
+/* Extract number from this (may be a string, or a number literal) */
+bool json_to_u32(const char *buffer, const jsmntok_t *tok,
+                 uint32_t *num);
+
 /* Extract number from this (may be a string, or a number literal) */
 bool json_to_u16(const char *buffer, const jsmntok_t *tok,
                  uint16_t *num);