diff --git a/src/ArchC-Core/ProcessorInstruction.class.st b/src/ArchC-Core/ProcessorInstruction.class.st
index 86af1bb..b026871 100644
--- a/src/ArchC-Core/ProcessorInstruction.class.st
+++ b/src/ArchC-Core/ProcessorInstruction.class.st
@@ -6,9 +6,6 @@ When the PDL spec is initially parsed, the ""instrictions"" Dictionary is filled
 Class {
 	#name : #ProcessorInstruction,
 	#superclass : #ProcessorInstructionDeclaration,
-	#instVars : [
-		'binaryEncoding'
-	],
 	#category : #'ArchC-Core-Core'
 }
 
diff --git a/src/ArchC-Core/ProcessorInstructionDeclaration.class.st b/src/ArchC-Core/ProcessorInstructionDeclaration.class.st
index e38c8da..9764e50 100644
--- a/src/ArchC-Core/ProcessorInstructionDeclaration.class.st
+++ b/src/ArchC-Core/ProcessorInstructionDeclaration.class.st
@@ -12,7 +12,8 @@ Class {
 		'format',
 		'internalBindings',
 		'syntax',
-		'isa'
+		'isa',
+		'binaryEncoding'
 	],
 	#classVars : [
 		'EmptyBindings'
@@ -132,7 +133,10 @@ ProcessorInstructionDeclaration >> assertInvariants [
 
 { #category : #accessing }
 ProcessorInstructionDeclaration >> binaryEncoding [
-	^format binaryEncoding inEnvironment: internalBindings
+	binaryEncoding isNil ifTrue: [
+		binaryEncoding := format binaryEncoding inEnvironment: internalBindings.
+	].
+	^ binaryEncoding
 ]
 
 { #category : #accessing }