diff --git a/legacy/firmware/.changelog.d/1854.fixed b/legacy/firmware/.changelog.d/1854.fixed
new file mode 100644
index 0000000000..de09538267
--- /dev/null
+++ b/legacy/firmware/.changelog.d/1854.fixed
@@ -0,0 +1 @@
+Fix incorrect compile-time check of maximum protobuf message size.
diff --git a/legacy/firmware/messages.h b/legacy/firmware/messages.h
index fa8fc1d30e..ad362922c0 100644
--- a/legacy/firmware/messages.h
+++ b/legacy/firmware/messages.h
@@ -29,7 +29,7 @@
 #define MSG_HEADER_SIZE 9
 
 // Maximum size of an incoming protobuf-encoded message without headers.
-#define MSG_IN_ENCODED_SIZE (15 * 1024)
+#define MSG_IN_ENCODED_SIZE (16 * 1024)
 
 // Maximum size of a C struct containing a decoded incoming message.
 #define MSG_IN_DECODED_SIZE (15 * 1024)
diff --git a/legacy/firmware/protob/messages_map.py b/legacy/firmware/protob/messages_map.py
index f6f9a3a2b8..f901d3492b 100755
--- a/legacy/firmware/protob/messages_map.py
+++ b/legacy/firmware/protob/messages_map.py
@@ -97,7 +97,7 @@ def handle_message(fh, fl, skipped, message):
 
     if encoded_size:
         fl.write(
-            f'_Static_assert({encoded_size} >= sizeof({short_name}_size), "msg buffer too small");\n'
+            f'_Static_assert({encoded_size} >= {short_name}_size, "msg buffer too small");\n'
         )
 
     if decoded_size: