diff --git a/spec/message.abnf b/spec/message.abnf
index 04ad7c8fe..6c72deeb4 100644
--- a/spec/message.abnf
+++ b/spec/message.abnf
@@ -5,7 +5,7 @@ simple-start      = simple-start-char / escaped-char / placeholder
 pattern           = *(text-char / escaped-char / placeholder)
 placeholder       = expression / markup
 
-complex-message   = *(declaration [s]) complex-body
+complex-message   = *(declaration [s]) complex-body [s]
 declaration       = input-declaration / local-declaration / reserved-statement
 complex-body      = quoted-pattern / matcher
 
diff --git a/spec/syntax.md b/spec/syntax.md
index 3376f65e2..0e1ed3ae0 100644
--- a/spec/syntax.md
+++ b/spec/syntax.md
@@ -168,9 +168,10 @@ and consists of:
 
 1. an optional list of _declarations_, followed by
 2. a _complex body_
+3. optional trailing whitespace
 
 ```abnf
-complex-message = *(declaration [s]) complex-body
+complex-message = *(declaration [s]) complex-body [s]
 ```
 
 ### Declarations
diff --git a/test/tests/syntax.json b/test/tests/syntax.json
index 7206e9f06..1364ba565 100644
--- a/test/tests/syntax.json
+++ b/test/tests/syntax.json
@@ -409,6 +409,11 @@
           "type": "unsupported-statement"
         }
       ]
+    },
+    {
+      "src": "{{trailing whitespace}} \n",
+      "expCleanSrc": "trailing whitespace",
+      "exp": "trailing whitespace"
     }
   ]
 }