diff --git a/src/ThreadedFFI-UFFI-Tests/TFUFFIConcurrencyTest.class.st b/src/ThreadedFFI-UFFI-Tests/TFUFFIConcurrencyTest.class.st
new file mode 100644
index 00000000000..51a36e61b66
--- /dev/null
+++ b/src/ThreadedFFI-UFFI-Tests/TFUFFIConcurrencyTest.class.st
@@ -0,0 +1,80 @@
+Class {
+	#name : #TFUFFIConcurrencyTest,
+	#superclass : #TFUFFITestCase,
+	#instVars : [
+		'p1',
+		'p2'
+	],
+	#category : #'ThreadedFFI-UFFI-Tests'
+}
+
+{ #category : #'ffi-calls' }
+TFUFFIConcurrencyTest >> booleanToInt: boolean [
+
+	^ self ffiCall: #(int id_int(Boolean boolean))	
+]
+
+{ #category : #'ffi-calls' }
+TFUFFIConcurrencyTest >> methodCallingBooleanToInt [
+
+	^ self booleanToInt: true
+]
+
+{ #category : #running }
+TFUFFIConcurrencyTest >> tearDown [
+
+	FFIMethodRegistry uniqueInstance resetSingleClass: self class.
+
+	p1 ifNotNil: #terminate.
+	p2 ifNotNil: #terminate.
+
+	(self class >> #booleanToInt: hasProperty: #ffiNonCompiledMethod)
+		ifTrue: [
+			self class compile: '
+booleanToInt: boolean
+
+	^ self ffiCall: #(int id_int(Boolean boolean))	' ].
+	super tearDown
+]
+
+{ #category : #tests }
+TFUFFIConcurrencyTest >> testConcurrentlyCompiling [
+
+	| barrier finish installedMethod nonCompiledMethod |
+	self deny:
+		(self class >> #booleanToInt: hasProperty: #ffiNonCompiledMethod).
+
+	barrier := Semaphore new.
+	finish := Semaphore new.
+
+
+	p1 := [
+	      [
+	      barrier wait.
+	      self methodCallingBooleanToInt.
+	      finish signal ] repeat ] forkAt: 39.
+
+	p2 := [
+	      [
+	      barrier wait.
+	      self methodCallingBooleanToInt.
+	      finish signal ] repeat ] forkAt: 39.
+
+	500 timesRepeat: [
+		
+		FFIMethodRegistry uniqueInstance resetSingleClass: self class.
+		
+		barrier
+			signal;
+			signal.
+		finish
+			wait;
+			wait.
+
+		installedMethod := self class >> #booleanToInt:.
+		nonCompiledMethod := installedMethod propertyAt:
+			                     #ffiNonCompiledMethod.
+
+		self assert: (installedMethod hasProperty: #ffiNonCompiledMethod).
+		self deny: (nonCompiledMethod hasProperty: #ffiNonCompiledMethod) ]
+]
diff --git a/src/UnifiedFFI/FFICalloutAPI.class.st b/src/UnifiedFFI/FFICalloutAPI.class.st
index fdde299f456..be02fc57ab1 100644
--- a/src/UnifiedFFI/FFICalloutAPI.class.st
+++ b/src/UnifiedFFI/FFICalloutAPI.class.st
@@ -125,7 +125,7 @@ FFICalloutAPI >> function: functionSignature library: moduleNameOrLibrary [
 		methodClass: sender methodClass.	"Replace with generated ffi method, but save old one for future use"
 	ffiMethod
 		propertyAt: #ffiNonCompiledMethod
-		put: (sender methodClass methodDict at: sender selector).	"For senders search, one need to keep the selector in the properties"
+		put: sender method.	"For senders search, one need to keep the selector in the properties"
 	ffiMethod propertyAt: #ffiMethodSelector put: ffiMethodSelector.
 	sender methodClass methodDict at: sender selector put: ffiMethod.	"Register current method as compiled for ffi"
 	FFIMethodRegistry uniqueInstance registerMethod: ffiMethod.	"Resend"