diff --git a/model/model-common/src/main/java/com/evolveum/midpoint/model/common/expression/script/AbstractCachingScriptEvaluator.java b/model/model-common/src/main/java/com/evolveum/midpoint/model/common/expression/script/AbstractCachingScriptEvaluator.java
index 43f52f6fbcd..8aec070b2a5 100644
--- a/model/model-common/src/main/java/com/evolveum/midpoint/model/common/expression/script/AbstractCachingScriptEvaluator.java
+++ b/model/model-common/src/main/java/com/evolveum/midpoint/model/common/expression/script/AbstractCachingScriptEvaluator.java
@@ -11,6 +11,9 @@
 import java.util.List;
 import javax.xml.namespace.QName;
 
+import com.evolveum.midpoint.util.DOMUtil;
+import com.evolveum.midpoint.util.QNameUtil;
+
 import org.jetbrains.annotations.NotNull;
 
 import com.evolveum.midpoint.common.LocalizationService;
@@ -90,25 +93,7 @@ public <T, V extends PrismValue> List<V> evaluate(ScriptExpressionEvaluationCont
             return evalPrismValues;
         }
 
-        QName xsdReturnType = context.getOutputDefinition().getTypeName();
-
-        Class<T> javaReturnType = XsdTypeMapper.toJavaType(xsdReturnType);
-        if (javaReturnType == null) {
-            javaReturnType = getPrismContext().getSchemaRegistry().getCompileTimeClass(xsdReturnType);
-        }
-
-        if (javaReturnType == null && (context.getOutputDefinition() instanceof PrismContainerDefinition<?>)) {
-            // This is the case when we need a container, but we do not have compile-time class for that
-            // E.g. this may be container in object extension (MID-5080)
-            javaReturnType = (Class<T>) PrismContainerValue.class;
-        }
-
-        if (javaReturnType == null) {
-            // TODO quick and dirty hack - because this could be because of enums defined in schema extension (MID-2399)
-            // ...and enums (xsd:simpleType) are not parsed into ComplexTypeDefinitions
-            javaReturnType = (Class<T>) String.class;
-        }
-        LOGGER.trace("expected return type: XSD={}, Java={}", xsdReturnType, javaReturnType);
+        Class<T> javaReturnType = determineJavaReturnType(context);
 
         List<V> values = new ArrayList<>();
 
@@ -132,6 +117,36 @@ public <T, V extends PrismValue> List<V> evaluate(ScriptExpressionEvaluationCont
         return values;
     }
 
+    @NotNull
+    private <T> Class<T> determineJavaReturnType(ScriptExpressionEvaluationContext context) {
+        QName xsdReturnType = context.getOutputDefinition().getTypeName();
+
+        // Ugly hack. Indented to allow xsd:anyType return type, see MID-6775.
+        if (QNameUtil.match(xsdReturnType, DOMUtil.XSD_ANYTYPE)) {
+            //noinspection unchecked
+            return (Class<T>) Object.class;
+        }
+
+        Class<T> javaReturnType = XsdTypeMapper.toJavaType(xsdReturnType);
+        if (javaReturnType == null) {
+            javaReturnType = getPrismContext().getSchemaRegistry().getCompileTimeClass(xsdReturnType);
+        }
+
+        if (javaReturnType == null && (context.getOutputDefinition() instanceof PrismContainerDefinition<?>)) {
+            // This is the case when we need a container, but we do not have compile-time class for that
+            // E.g. this may be container in object extension (MID-5080)
+            javaReturnType = (Class<T>) PrismContainerValue.class;
+        }
+
+        if (javaReturnType == null) {
+            // TODO quick and dirty hack - because this could be because of enums defined in schema extension (MID-2399)
+            //  ...and enums (xsd:simpleType) are not parsed into ComplexTypeDefinitions
+            javaReturnType = (Class<T>) String.class;
+        }
+        LOGGER.trace("expected return type: XSD={}, Java={}", xsdReturnType, javaReturnType);
+        return javaReturnType;
+    }
+
     private C getCompiledScript(String codeString, ScriptExpressionEvaluationContext context) throws ExpressionEvaluationException, SecurityViolationException {
         C compiledScript = scriptCache.getCode(context.getExpressionProfile(), codeString);
         if (compiledScript != null) {
diff --git a/model/model-impl/src/test/java/com/evolveum/midpoint/model/impl/expr/TestModelExpressions.java b/model/model-impl/src/test/java/com/evolveum/midpoint/model/impl/expr/TestModelExpressions.java
index e8509da4f04..feec6ff3087 100644
--- a/model/model-impl/src/test/java/com/evolveum/midpoint/model/impl/expr/TestModelExpressions.java
+++ b/model/model-impl/src/test/java/com/evolveum/midpoint/model/impl/expr/TestModelExpressions.java
@@ -307,8 +307,25 @@ public void testCustomFunctionWrongParameter() throws Exception {
         }
     }
 
+    @Test
+    public void testCustomFunctionUntyped() throws Exception {
+        PrismContainer<Containerable> customPc = createCustomContainer();
+        PrismContainerValue<Containerable> customPcv = createCustomValue();
+
+        VariablesMap variables = VariablesMap.create(prismContext,
+                "var1", customPc.clone().getValues(), customPc.getDefinition(),
+                "var2", customPcv.clone(), customPcv.getDefinition());
+
+        assertExecuteScriptExpressionString(variables, "s-1");
+    }
+
     @NotNull
     private PrismContainerValue<Containerable> createCustomValue() throws SchemaException {
+        return createCustomContainer().getValue();
+    }
+
+    @NotNull
+    private PrismContainer<Containerable> createCustomContainer() throws SchemaException {
         PrismContainerDefinition<Containerable> customDef =
                 prismContext.getSchemaRegistry().findContainerDefinitionByElementName(CUSTOM);
         PrismContainer<Containerable> customPc = customDef.instantiate();
@@ -320,7 +337,7 @@ private PrismContainerValue<Containerable> createCustomValue() throws SchemaExce
 
         customPcv.add(stringPp);
         customPcv.add(intPp);
-        return customPcv;
+        return customPc;
     }
 
     private void assertExecuteScriptExpressionString(
@@ -335,7 +352,8 @@ private String executeScriptExpressionString(VariablesMap variables)
             throws SecurityViolationException, ExpressionEvaluationException, SchemaException,
             ObjectNotFoundException, CommunicationException, ConfigurationException, IOException {
         // GIVEN
-        OperationResult result = createOperationResult();
+        Task task = getTestTask();
+        OperationResult result = task.getResult();
         String shortTestName = getTestNameShort();
 
         ScriptExpressionEvaluatorType scriptType = parseScriptType("expression-" + shortTestName + ".xml");
@@ -374,7 +392,8 @@ private String executeScriptExpressionString(VariablesMap variables)
 
     @SuppressWarnings("SameParameterValue")
     private <T> List<PrismPropertyValue<T>> evaluate(ScriptExpression scriptExpression, VariablesMap variables, boolean useNew,
-            String contextDescription, Task task, OperationResult result) throws ExpressionEvaluationException, ObjectNotFoundException, SchemaException, CommunicationException, ConfigurationException, SecurityViolationException {
+            String contextDescription, Task task, OperationResult result) throws ExpressionEvaluationException,
+            ObjectNotFoundException, SchemaException, CommunicationException, ConfigurationException, SecurityViolationException {
         if (task == null) {
             task = taskManager.createTaskInstance();
         }
@@ -394,5 +413,4 @@ private <T> List<PrismPropertyValue<T>> evaluate(ScriptExpression scriptExpressi
             ModelExpressionThreadLocalHolder.popExpressionEnvironment();
         }
     }
-
 }
diff --git a/model/model-impl/src/test/resources/expr/expression-testCustomFunctionUntyped.xml b/model/model-impl/src/test/resources/expr/expression-testCustomFunctionUntyped.xml
new file mode 100644
index 00000000000..0e4f5abb256
--- /dev/null
+++ b/model/model-impl/src/test/resources/expr/expression-testCustomFunctionUntyped.xml
@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright (c) 2010-2017 Evolveum and contributors
+  ~
+  ~ This work is dual-licensed under the Apache License 2.0
+  ~ and European Union Public License. See LICENSE file for details.
+  -->
+
+<script xmlns="http://midpoint.evolveum.com/xml/ns/public/common/common-3">
+    <code>
+        import com.evolveum.midpoint.prism.path.ItemPath
+
+        pcv = functionLibrary.execute("untyped", [container: var1, containerValue: var2])
+        pcv?.findProperty(ItemPath.create('stringValue'))?.getRealValue() + '-' +
+                pcv?.findProperty(ItemPath.create('intValue'))?.getRealValue()
+    </code>
+</script>
diff --git a/model/model-impl/src/test/resources/expr/function-library.xml b/model/model-impl/src/test/resources/expr/function-library.xml
index 8284839e944..e4caeb9bdf1 100644
--- a/model/model-impl/src/test/resources/expr/function-library.xml
+++ b/model/model-impl/src/test/resources/expr/function-library.xml
@@ -35,4 +35,28 @@
             </code>
         </script>
     </function>
+
+    <function>
+        <name>untyped</name>
+        <parameter>
+            <name>container</name>
+            <!-- Although it is possible to provide a PrismContainer here, it is more advisable
+                 to send a list of PrismContainerValues. (Just BTW, we can use a specific type then!) -->
+            <type>xsd:anyType</type>
+        </parameter>
+        <parameter>
+            <name>containerValue</name>
+            <type>xsd:anyType</type> <!-- Expects PrismContainerValue. Let us assume it is of any type. -->
+        </parameter>
+        <returnType>xsd:anyType</returnType> <!-- Returns PrismContainerValue -->
+        <script>
+            <code>
+                import com.evolveum.prism.xml.ns._public.types_3.ItemType
+
+                log.info('container = {} ({})', container, container?.class)
+                log.info('containerValue = {} ({})', containerValue, containerValue?.class)
+                container?.get(0)
+            </code>
+        </script>
+    </function>
 </functionLibrary>