diff --git a/codec/SMPPBodyBase.st b/codec/SMPPBodyBase.st
index 7483a26..7d3a2d0 100644
--- a/codec/SMPPBodyBase.st
+++ b/codec/SMPPBodyBase.st
@@ -164,7 +164,7 @@ sub-classes will provide the specific bodies.'>
             aHeader commandId = each messageType
                 ifTrue: [^each new readFrom: aStream]].
 
-        ^self error: 'No handler for command id = %1' % aHeader commandId displayString.
+        ^self error: 'No handler for command id = %1' % {aHeader commandId displayString}.
     ]
 
     readFrom: aStream [