diff --git a/applications/message_handler/lib/message_queue.cpp b/applications/message_handler/lib/message_queue.cpp
index c3890fe..4001f8c 100644
--- a/applications/message_handler/lib/message_queue.cpp
+++ b/applications/message_handler/lib/message_queue.cpp
@@ -48,7 +48,7 @@
 }
 
 size_t QueueImpl::capacity() const {
-    return queue.header.size - available();
+    return queue.header.size - available() - 1;
 }
 
 bool QueueImpl::read(uint8_t *dst, uint32_t length) {