diff --git a/src/main/scala/org/camunda/feel/impl/builtin/BuiltinFunction.scala b/src/main/scala/org/camunda/feel/impl/builtin/BuiltinFunction.scala
index 007fd632b..8d9368029 100644
--- a/src/main/scala/org/camunda/feel/impl/builtin/BuiltinFunction.scala
+++ b/src/main/scala/org/camunda/feel/impl/builtin/BuiltinFunction.scala
@@ -16,8 +16,7 @@
  */
 package org.camunda.feel.impl.builtin
 
-import org.camunda.feel.logger
-import org.camunda.feel.syntaxtree.{Val, ValError, ValFatalError, ValFunction, ValNull}
+import org.camunda.feel.syntaxtree.{Val, ValError, ValFunction}
 
 object BuiltinFunction {
 
@@ -33,13 +32,9 @@ object BuiltinFunction {
     )
   }
 
-  private def error: PartialFunction[List[Val], Any] = {
-    case args if args.exists(_.isInstanceOf[ValFatalError]) =>
-      args.find(_.isInstanceOf[ValFatalError])
-    case args if args.exists(_.isInstanceOf[ValError])      => args.find(_.isInstanceOf[ValError])
-    case args                                               =>
-      val argumentList = args.map("'" + _ + "'").mkString(", ")
-      ValError(s"Illegal arguments: $argumentList")
+  private def error: PartialFunction[List[Val], Any] = { case args =>
+    val argumentList = args.map("'" + _ + "'").mkString(", ")
+    ValError(s"Illegal arguments: $argumentList")
   }
 
 }
diff --git a/src/main/scala/org/camunda/feel/impl/interpreter/FeelInterpreter.scala b/src/main/scala/org/camunda/feel/impl/interpreter/FeelInterpreter.scala
index 60072b841..f721a22fc 100644
--- a/src/main/scala/org/camunda/feel/impl/interpreter/FeelInterpreter.scala
+++ b/src/main/scala/org/camunda/feel/impl/interpreter/FeelInterpreter.scala
@@ -249,6 +249,7 @@ class FeelInterpreter(private val valueMapper: ValueMapper) {
             findFunction(context, name, params),
             f =>
               invokeFunction(f, params) match {
+                case fatalError: ValFatalError             => fatalError
                 case ValError(failure) if name == "assert" =>
                   error(EvaluationFailureType.ASSERT_FAILURE, failure)
                   ValError(failure)
@@ -727,10 +728,19 @@ class FeelInterpreter(private val valueMapper: ValueMapper) {
       }
     }
 
-    function.invoke(paramList) match {
-      case fatalError: ValFatalError => fatalError
-      case e: ValError               => e
-      case result                    => context.valueMapper.toVal(result)
+    // validate parameters
+    if (paramList.exists(_.isInstanceOf[ValFatalError])) {
+      paramList.find(_.isInstanceOf[ValFatalError]).get
+
+    } else if (paramList.exists(_.isInstanceOf[ValError])) {
+      paramList.find(_.isInstanceOf[ValError]).get
+
+    } else {
+      function.invoke(paramList) match {
+        case fatalError: ValFatalError => fatalError
+        case e: ValError               => e
+        case result                    => context.valueMapper.toVal(result)
+      }
     }
   }
 
diff --git a/src/test/scala/org/camunda/feel/impl/interpreter/InterpreterUnaryTest.scala b/src/test/scala/org/camunda/feel/impl/interpreter/InterpreterUnaryTest.scala
index c5db4f30e..fbdb8fa3d 100644
--- a/src/test/scala/org/camunda/feel/impl/interpreter/InterpreterUnaryTest.scala
+++ b/src/test/scala/org/camunda/feel/impl/interpreter/InterpreterUnaryTest.scala
@@ -529,7 +529,7 @@ class InterpreterUnaryTest
     evaluateUnaryTests("null", inputValue = null) should returnResult(true)
   }
 
-  "A function" should "be invoked with ? (input value)" in {
+  "A function" should "be invoked with the special variable '?'" in {
 
     evaluateUnaryTests(""" starts with(?, "f") """, "foo") should returnResult(true)
     evaluateUnaryTests(""" starts with(?, "b") """, "foo") should returnResult(false)
@@ -541,6 +541,12 @@ class InterpreterUnaryTest
     evaluateUnaryTests("< min(1,2,3)", 2) should returnResult(false)
   }
 
+  it should "be invoked with the special variable '?' for a parameter with ANY type" in {
+
+    evaluateUnaryTests("list contains([481, 485, 551, 483], ?)", 481) should returnResult(true)
+    evaluateUnaryTests("list contains([481, 485, 551, 483], ?)", 999) should returnResult(false)
+  }
+
   "A unary-tests expression" should "return true if it evaluates to a value that is equal to the implicit value" in {
 
     evaluateUnaryTests("5", 5) should returnResult(true)