diff --git a/.smalltalk.ston b/.smalltalk.ston
index f5cdb4f..9f9c852 100644
--- a/.smalltalk.ston
+++ b/.smalltalk.ston
@@ -8,7 +8,7 @@ SmalltalkCISpec {
   ],
   #testing : {
     #exclude : {
-      #packages : [ 'OSSubprocess-Tests-Unit' ]
+      #packages : [ 'OSSubprocess-Tests-Stress' ]
     }
   }
 }
diff --git a/.stress.smalltalk.ston b/.stress.smalltalk.ston
index c54cc22..7e6e1af 100644
--- a/.stress.smalltalk.ston
+++ b/.stress.smalltalk.ston
@@ -7,8 +7,8 @@ SmalltalkCISpec {
     }
   ],
   #testing : {
-    #include : {
-        #packages : [ 'OSSubprocess-Tests-Stress' ]
+    #exclude : {
+        #packages : [ 'OSSubprocess-Tests-Unit' ]
     }
   }
 }
diff --git a/repository/OSSubprocess/OSSUnixSubprocess.class.st b/repository/OSSubprocess/OSSUnixSubprocess.class.st
index 62cfb04..d8d098b 100644
--- a/repository/OSSubprocess/OSSUnixSubprocess.class.st
+++ b/repository/OSSubprocess/OSSUnixSubprocess.class.st
@@ -1181,7 +1181,9 @@ OSSUnixSubprocess >> waitForExitWithTimeout: aDuration [
 	exitStatus ifNotNil: [ ^ exitStatus ].
 
 	mutexForSigchld := Semaphore new.
-	expired := mutexForSigchld waitTimeoutMSecs: aDuration asMilliSeconds.
+	expired := SystemVersion current major < 12
+		ifTrue: [ mutexForSigchld waitTimeoutMSecs: aDuration asMilliSeconds ]
+		ifFalse: [ mutexForSigchld waitTimeoutMilliseconds: aDuration asMilliSeconds ].
 	expired ifTrue: [ OSSTimeout signal: 'Process not finished after ', aDuration asString ].
 	^ exitStatus  
 ]