diff --git a/processor/src/main/java/org/mapstruct/ap/model/assignment/MethodReference.java b/processor/src/main/java/org/mapstruct/ap/model/assignment/MethodReference.java
index 60bb09718..c6842ce59 100644
--- a/processor/src/main/java/org/mapstruct/ap/model/assignment/MethodReference.java
+++ b/processor/src/main/java/org/mapstruct/ap/model/assignment/MethodReference.java
@@ -23,11 +23,11 @@ import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
+
 import org.mapstruct.ap.model.Assignment;
 import org.mapstruct.ap.model.FactoryMethod;
 import org.mapstruct.ap.model.MapperReference;
 import org.mapstruct.ap.model.MappingMethod;
-
 import org.mapstruct.ap.model.common.ConversionContext;
 import org.mapstruct.ap.model.common.Parameter;
 import org.mapstruct.ap.model.common.Type;
@@ -74,7 +74,7 @@ public class MethodReference extends MappingMethod implements Assignment, Factor
         super( method );
         this.declaringMapper = declaringMapper;
         this.contextParam = null;
-        Set<Type> imported = new HashSet( method.getThrownTypes() );
+        Set<Type> imported = new HashSet<Type>( method.getThrownTypes() );
         if ( targetType != null ) {
             imported.add( targetType );
         }
@@ -130,7 +130,7 @@ public class MethodReference extends MappingMethod implements Assignment, Factor
 
     @Override
     public Set<Type> getImportTypes() {
-        Set<Type> imported = org.mapstruct.ap.util.Collections.asSet( importTypes, super.getImportTypes() );
+        Set<Type> imported = new HashSet<Type>( importTypes );
         if ( assignment != null ) {
             imported.addAll( assignment.getImportTypes() );
         }
diff --git a/processor/src/test/java/org/mapstruct/ap/test/imports/ConflictingTypesNamesTest.java b/processor/src/test/java/org/mapstruct/ap/test/imports/ConflictingTypesNamesTest.java
index 44a46260c..66475c52b 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/imports/ConflictingTypesNamesTest.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/imports/ConflictingTypesNamesTest.java
@@ -95,7 +95,13 @@ public class ConflictingTypesNamesTest {
         assertThat( target ).isNotNull();
         assertThat( target.getNotImported() ).isSameAs( source.getNotImported() );
 
+        target = SecondSourceTargetMapper.INSTANCE.sourceToTarget( source );
+
+        assertThat( target ).isNotNull();
+        assertThat( target.getNotImported() ).isSameAs( source.getNotImported() );
+
         generatedSource.forMapper( SourceTargetMapper.class ).containsNoImportFor( NotImportedDatatype.class );
+        generatedSource.forMapper( SecondSourceTargetMapper.class ).containsNoImportFor( NotImportedDatatype.class );
     }
 
     @Test
diff --git a/processor/src/test/java/org/mapstruct/ap/test/imports/SecondSourceTargetMapper.java b/processor/src/test/java/org/mapstruct/ap/test/imports/SecondSourceTargetMapper.java
index 225ad9673..3023af033 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/imports/SecondSourceTargetMapper.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/imports/SecondSourceTargetMapper.java
@@ -20,6 +20,8 @@ package org.mapstruct.ap.test.imports;
 
 import org.mapstruct.Mapper;
 import org.mapstruct.ap.test.imports.referenced.GenericMapper;
+import org.mapstruct.ap.test.imports.referenced.Source;
+import org.mapstruct.ap.test.imports.referenced.Target;
 import org.mapstruct.ap.test.imports.to.FooWrapper;
 import org.mapstruct.factory.Mappers;
 
@@ -32,4 +34,6 @@ public interface SecondSourceTargetMapper {
     SecondSourceTargetMapper INSTANCE = Mappers.getMapper( SecondSourceTargetMapper.class );
 
     FooWrapper fooWrapperToFooWrapper(org.mapstruct.ap.test.imports.from.FooWrapper foo);
+
+    Target sourceToTarget(Source source);
 }
diff --git a/processor/src/test/java/org/mapstruct/ap/test/imports/referenced/GenericMapper.java b/processor/src/test/java/org/mapstruct/ap/test/imports/referenced/GenericMapper.java
index e127cf51e..20da025c6 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/imports/referenced/GenericMapper.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/imports/referenced/GenericMapper.java
@@ -37,4 +37,8 @@ public class GenericMapper {
 
         return null;
     }
+
+    public NotImportedDatatype identity(NotImportedDatatype notImported) {
+        return notImported;
+    }
 }