diff --git a/src/modules/module-protocol-pulse/message.c b/src/modules/module-protocol-pulse/message.c
index 19b4f82d6..bbeb7e99e 100644
--- a/src/modules/module-protocol-pulse/message.c
+++ b/src/modules/module-protocol-pulse/message.c
@@ -383,9 +383,12 @@ static int ensure_size(struct message *m, uint32_t size)
 	if (m->length > m->allocated)
 		return -ENOMEM;
 
-	if (m->length + size <= m->allocated)
+	if (size <= m->allocated - m->length)
 		return size;
 
+	if (m->allocated + size < m->allocated)
+		return -ENOMEM;
+
 	alloc = SPA_ROUND_UP_N(SPA_MAX(m->allocated + size, 4096u), 4096u);
 	diff = alloc - m->allocated;
 	if ((data = realloc(m->data, alloc)) == NULL) {