diff --git a/src/UnifiedFFI-Tests/FFIValueHolderTest.class.st b/src/UnifiedFFI-Tests/FFIValueHolderTest.class.st
index 5c942909ba2..6e11949ac52 100644
--- a/src/UnifiedFFI-Tests/FFIValueHolderTest.class.st
+++ b/src/UnifiedFFI-Tests/FFIValueHolderTest.class.st
@@ -321,6 +321,33 @@ FFIValueHolderTest >> testCallStructPointerPointerWithValueHolder [
 	holder value getHandle free.
 ]
 
+{ #category : 'tests' }
+FFIValueHolderTest >> testCallStructureWithReference [
+	| struct holder result |
+	
+	struct := FFITestStructure new.
+	holder := struct referenceTo.
+	
+	"this simulates a c function like this: 
+	int aFunction(FFITestStructure *aValue) {
+		aValue->byteValue = 42;
+		return 1;
+	}"
+	FFICallbackFunctionResolution 
+		registerCallback: (FFICallback 
+			signature: #(int (void *aValue)) 
+			block: [ :aValue |
+				(FFITestStructure fromHandle: aValue) byte: 42.
+				1 ])
+		as: #TestStructureValueHolder.
+	self assert: struct byte equals: 0.
+
+	result := self ffiMethodStructure: holder.
+	
+	self assert: result equals: 1.
+	self assert: struct byte equals: 42
+]
+
 { #category : 'tests' }
 FFIValueHolderTest >> testCallStructureWithValueHolder [
 	| holder result resultStruct |
@@ -364,11 +391,12 @@ FFIValueHolderTest >> testOpaqueObjectTypeCanBeHolded [
 FFIValueHolderTest >> testStructureTypeCanBeHolded [
 	| holder |
 	
+	"a holder of the structure is the handle of the structure itself, since from the POV 
+	 of uFFI is the same to pass `AStruct arg` than `AStruct *arg` sinie the argument 
+	 mangling will be aquivalent (this maybe should be review)?" 
+	
 	holder :=  FFITestStructure newValueHolder.
 	self assert: holder type class equals: FFITestStructure.
 	self assert: (holder getHandle isKindOf: ByteArray).
-	self assert: holder getHandle size equals: FFITestStructure newBuffer size.	
-	"this can't be like this (the structure tries to be filled with the handle)"
-	"holder value: (structClass fromHandle: (ExternalAddress fromAddress: 42)).
-	self assert: holder value getHandle equals: (ExternalAddress fromAddress: 42)"
+	self assert: holder getHandle size equals: FFITestStructure structureSize
 ]
diff --git a/src/UnifiedFFI/FFIArray.class.st b/src/UnifiedFFI/FFIArray.class.st
index 7fffbb166b5..e5caadbf68e 100644
--- a/src/UnifiedFFI/FFIArray.class.st
+++ b/src/UnifiedFFI/FFIArray.class.st
@@ -173,3 +173,15 @@ FFIArray class >> type: aType 	size: elements [
 	type := aType.
 	numberOfElements := elements
 ]
+
+{ #category : 'converting' }
+FFIArray >> packToArity: arity [
+	"in fact, an FFIArray has a 'natural' arity of 1 + the arity of the contained type. 
+	Which means to box it (pack it) to an arity, first we have to substract that value."
+	| realArity |
+	
+	realArity := arity - self type naturalPointerArity.
+	^ realArity > 1
+		ifTrue: [ super packToArity: realArity ]
+		ifFalse: [ self ]
+]
diff --git a/src/UnifiedFFI/FFIEnumeration.class.st b/src/UnifiedFFI/FFIEnumeration.class.st
index da16e6ec392..fb9c5362a5a 100644
--- a/src/UnifiedFFI/FFIEnumeration.class.st
+++ b/src/UnifiedFFI/FFIEnumeration.class.st
@@ -312,10 +312,17 @@ FFIEnumeration class >> representationType [
 
 { #category : 'comparing' }
 FFIEnumeration >> = anEnumInst [
+
 	^ self class == anEnumInst class
 		and: [ self value = anEnumInst value ]
 ]
 
+{ #category : 'comparing' }
+FFIEnumeration >> hash [
+
+	^ self class hash bitXor: self value
+]
+
 { #category : 'accessing' }
 FFIEnumeration >> item [
 	^ self class itemAt: value
diff --git a/src/UnifiedFFI/FFIExternalObjectType.class.st b/src/UnifiedFFI/FFIExternalObjectType.class.st
index 4f461233993..2212cf90c37 100644
--- a/src/UnifiedFFI/FFIExternalObjectType.class.st
+++ b/src/UnifiedFFI/FFIExternalObjectType.class.st
@@ -11,8 +11,9 @@ Class {
 
 { #category : 'initialization' }
 FFIExternalObjectType >> initialize [
+
 	super initialize.
-	pointerArity := self class naturalPointerArity
+	pointerArity := self naturalPointerArity
 ]
 
 { #category : 'accessing' }
diff --git a/src/UnifiedFFI/FFIExternalType.class.st b/src/UnifiedFFI/FFIExternalType.class.st
index edd2eed128b..d0e4de5c7ea 100644
--- a/src/UnifiedFFI/FFIExternalType.class.st
+++ b/src/UnifiedFFI/FFIExternalType.class.st
@@ -279,6 +279,12 @@ FFIExternalType >> loader: aLoader [
 	loader := aLoader
 ]
 
+{ #category : 'accessing' }
+FFIExternalType >> naturalPointerArity [
+
+	^ self class naturalPointerArity
+]
+
 { #category : 'testing' }
 FFIExternalType >> needsArityPacking [
 	"Regular types needs to be ''rolled'' if they are passed as pointers to its calling functions.
@@ -294,7 +300,7 @@ FFIExternalType >> needsArityPacking [
 	 Means that if I have a type that is naturally a pointer (for example an ExternalAddress, who
 	 is a 'void*'), it will have a natural arity of 1, then I pack if arity is bigger.
 	 Other cases could need to be rolled when pointer arity is diffrent."
-	^ self pointerArity > self class naturalPointerArity
+	^ self pointerArity > self naturalPointerArity
 ]
 
 { #category : 'testing' }
diff --git a/src/UnifiedFFI/FFIOop.class.st b/src/UnifiedFFI/FFIOop.class.st
index 9b6db2cbb76..5c0e639422c 100644
--- a/src/UnifiedFFI/FFIOop.class.st
+++ b/src/UnifiedFFI/FFIOop.class.st
@@ -33,9 +33,7 @@ FFIOop >> basicHandle: aHandle at: index [
 
 { #category : 'private' }
 FFIOop >> basicHandle: aHandle at: index put: value [
-	self error: 'Not sure I want to do this.'
-	"But it would be like this:
-	aHandle pointerAt: index put: value"
+	aHandle pointerAt: index put: value
 ]
 
 { #category : 'accessing' }
diff --git a/src/UnifiedFFI/FFIReferenceValueHolder.class.st b/src/UnifiedFFI/FFIReferenceValueHolder.class.st
index 9c7d90ce573..b8f4e86eff1 100644
--- a/src/UnifiedFFI/FFIReferenceValueHolder.class.st
+++ b/src/UnifiedFFI/FFIReferenceValueHolder.class.st
@@ -20,6 +20,14 @@ FFIReferenceValueHolder class >> newType: aType [
 		handle: FFIValueHolderHandle new
 ]
 
+{ #category : 'instance creation' }
+FFIReferenceValueHolder class >> newType: aType handle: aHandle size: aSize [
+
+	^ (self newType: aType handle: aHandle)
+		typeSize: aSize;
+		yourself
+]
+
 { #category : 'instance creation' }
 FFIReferenceValueHolder class >> newType: aType size: aNumber [
 
diff --git a/src/UnifiedFFI/FFIStructure.class.st b/src/UnifiedFFI/FFIStructure.class.st
index a8e8d18bfa4..59950db20d0 100644
--- a/src/UnifiedFFI/FFIStructure.class.st
+++ b/src/UnifiedFFI/FFIStructure.class.st
@@ -154,6 +154,11 @@ FFIStructure class >> compileFields: specArray withAccessors: aSymbol [
 { #category : 'private' }
 FFIStructure class >> compileMethodNamed: aSymbol code: aString classified: protocol [
 
+	"If we detect we have a method in the class with the right code but an equivalent is already in a superclass we can remove it to clean."
+	self
+		compiledMethodAt: aSymbol
+		ifPresent: [ :method | method sourceCode = aString and: [ method hasEquivalentMethodInSuperclass ifTrue: [ ^ method removeFromSystem ] ] ].
+
 	"If we already have the method we do not need to compile it. The method can come from a superclass having the same fields"
 	(self lookupSelector: aSymbol) ifNotNil: [ :method | method sourceCode = aString ifTrue: [ ^ self ] ].
 
@@ -312,9 +317,12 @@ FFIStructure class >> newBuffer [
 
 { #category : 'instance creation' }
 FFIStructure class >> newValueHolder [
-
+	| struct |
+	
+	struct := self new.
 	^ FFIReferenceValueHolder 
-		newType: self new 
+		newType: struct
+		handle: struct getHandle
 		size: self structureSize
 ]
 
@@ -446,3 +454,13 @@ FFIStructure >> printOn: aStream [
 			] separatedBy: [ aStream cr ].
 	aStream cr; nextPut: $)"
 ]
+
+{ #category : 'converting' }
+FFIStructure >> referenceTo [
+	"In fact, structures in uFFI are always passed by reference, then a referenceTo 
+	 it will always be itself"
+	 
+	 ^ FFIValueHolder 
+	 	newType: self
+	 	handle: self getHandle
+]