diff --git a/smalltalksrc/VMMaker/SpurMemoryManager.class.st b/smalltalksrc/VMMaker/SpurMemoryManager.class.st
index fa524e3056..d6cae225bb 100644
--- a/smalltalksrc/VMMaker/SpurMemoryManager.class.st
+++ b/smalltalksrc/VMMaker/SpurMemoryManager.class.st
@@ -8159,7 +8159,6 @@ SpurMemoryManager >> markAllUnscannedEphemerons [
 
 { #category : #'gc - global' }
 SpurMemoryManager >> markAndShouldScan: objOop [
-
 	"Helper for markAndTrace:.
 	 Mark the argument, and answer if its fields should be scanned now.
 	 Immediate objects don't need to be marked.
@@ -8167,24 +8166,29 @@ SpurMemoryManager >> markAndShouldScan: objOop [
 	 Pure bits objects don't need scanning, although their class does.
 	 Weak objects should be pushed on the weakling stack.
 	 Anything else need scanning."
-
-	<inline: true>
 	| format |
-	false ifTrue: [ ^ false ].
+	<inline: true>
+	(self isImmediate: objOop) ifTrue:
+		[^false].
+	"if markAndTrace: is to follow and eliminate forwarding pointers
+	 in its scan it cannot be handed an r-value which is forwarded."
 	self assert: (self isForwarded: objOop) not.
-	(self isMarked: objOop) ifTrue: [ ^ false ].
+	(self isMarked: objOop) ifTrue:
+		[^false].
 	self setIsMarkedOf: objOop to: true.
 	format := self formatOf: objOop.
-	(self isPureBitsFormat: format) ifTrue: [ "Avoid tracing classes of non-objects on the heap, e.g. IRC caches, Sista counters.""avoid pushing non-pointer objects on the markStack."
-		(self classIndexOf: objOop) > self lastClassIndexPun ifTrue: [ 
-			self markAndTraceClassOf: objOop ].
-		^ false ].
-	format = self weakArrayFormat ifTrue: [ "push weaklings on the weakling stack to scan later"
-		self push: objOop onObjStack: weaklingStack.
-		^ false ].
-	(format = self ephemeronFormat and: [ 
-		 self activeAndDeferredScan: objOop ]) ifTrue: [ ^ false ].
-	^ true
+	(self isPureBitsFormat: format) ifTrue: "avoid pushing non-pointer objects on the markStack."
+		["Avoid tracing classes of non-objects on the heap, e.g. IRC caches, Sista counters."
+		 (self classIndexOf: objOop) > self lastClassIndexPun ifTrue:
+			[self markAndTraceClassOf: objOop].
+		 ^false].
+	format = self weakArrayFormat ifTrue: "push weaklings on the weakling stack to scan later"
+		[self push: objOop onObjStack: weaklingStack.
+		 ^false].
+	(format = self ephemeronFormat
+	 and: [self activeAndDeferredScan: objOop]) ifTrue:
+		[^false].
+	^true
 ]
 
 { #category : #'gc - global' }