diff --git a/processor/src/main/java/org/mapstruct/ap/internal/model/source/MappingMethodOptions.java b/processor/src/main/java/org/mapstruct/ap/internal/model/source/MappingMethodOptions.java
index b7fd7f00d..859a4c6f5 100644
--- a/processor/src/main/java/org/mapstruct/ap/internal/model/source/MappingMethodOptions.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/model/source/MappingMethodOptions.java
@@ -230,9 +230,11 @@ public class MappingMethodOptions {
     }
 
     private boolean isRedefined(Set<String> redefinedNames, String inheritedName ) {
-        for ( String redefinedName : redefinedNames ) {
-            if ( elementsAreContainedIn( redefinedName, inheritedName ) ) {
-                return true;
+        if ( inheritedName != null ) {
+            for ( String redefinedName : redefinedNames ) {
+                if ( elementsAreContainedIn( inheritedName, redefinedName ) ) {
+                    return true;
+                }
             }
         }
         return false;
@@ -241,7 +243,7 @@ public class MappingMethodOptions {
     private boolean elementsAreContainedIn( String redefinedName, String inheritedName ) {
         if ( inheritedName != null && redefinedName.startsWith( inheritedName ) ) {
             // it is possible to redefine an exact matching source name, because the same source can be mapped to
-            // multiple targets. It is not possible for target, but caught by the Set and equals methoded in
+            // multiple targets. It is not possible for target, but caught by the Set and equals method in
             // MappingOptions. SourceName == null also could hint at redefinition
             if ( redefinedName.length() > inheritedName.length() ) {
                 // redefined.lenght() > inherited.length(), first following character should be separator
diff --git a/processor/src/test/java/org/mapstruct/ap/test/bugs/_2278/Issue2278MapperA.java b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2278/Issue2278MapperA.java
new file mode 100644
index 000000000..8527be3f8
--- /dev/null
+++ b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2278/Issue2278MapperA.java
@@ -0,0 +1,62 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._2278;
+
+import org.mapstruct.InheritInverseConfiguration;
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.factory.Mappers;
+
+/**
+ * ReproducerA
+ *
+ */
+@Mapper
+public interface Issue2278MapperA {
+
+    Issue2278MapperA INSTANCE = Mappers.getMapper( Issue2278MapperA.class );
+
+    @Mapping( target = "detailsDTO", source = "details" )
+    @Mapping( target = "detailsDTO.fuelType", ignore = true )
+    CarDTO map(Car in);
+
+    // checkout the Issue2278ReferenceMapper, the @InheritInverseConfiguration
+    // is de-facto @Mapping( target = "details", source = "detailsDTO" )
+    @InheritInverseConfiguration
+    @Mapping( target = "details.model", ignore = true )
+    @Mapping( target = "details.type", constant = "gto")
+    @Mapping( target = "details.fuel", source = "detailsDTO.fuelType")
+    Car map(CarDTO in);
+
+    class Car {
+        //CHECKSTYLE:OFF
+        public Details details;
+        //CHECKSTYLE:ON
+    }
+
+    class CarDTO {
+        //CHECKSTYLE:OFF
+        public DetailsDTO detailsDTO;
+        //CHECKSTYLE:ON
+    }
+
+    class Details {
+        //CHECKSTYLE:OFF
+        public String brand;
+        public String model;
+        public String type;
+        public String fuel;
+        //CHECKSTYLE:ON
+    }
+
+    class DetailsDTO {
+        //CHECKSTYLE:OFF
+        public String brand;
+        public String fuelType;
+        //CHECKSTYLE:ON
+    }
+
+}
diff --git a/processor/src/test/java/org/mapstruct/ap/test/bugs/_2278/Issue2278MapperB.java b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2278/Issue2278MapperB.java
new file mode 100644
index 000000000..b9d0abd52
--- /dev/null
+++ b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2278/Issue2278MapperB.java
@@ -0,0 +1,65 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._2278;
+
+import org.mapstruct.InheritInverseConfiguration;
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.factory.Mappers;
+
+/**
+ * ReproducerB
+ *
+ */
+@Mapper
+public interface Issue2278MapperB {
+
+    Issue2278MapperB INSTANCE = Mappers.getMapper( Issue2278MapperB.class );
+
+    // id mapping is cros-linked
+    @Mapping( target = "amount", source = "price" )
+    @Mapping( target = "detailsDTO.brand", source = "details.type" )
+    @Mapping( target = "detailsDTO.id1",  source = "details.id2" )
+    @Mapping( target = "detailsDTO.id2",  source = "details.id1" )
+    CarDTO map(Car in);
+
+    // inherit inverse, but undo cross-link in one sweep
+    @InheritInverseConfiguration // inherits all
+    @Mapping( target = "details", source = "detailsDTO" ) // resets everything on details <> detailsDto
+    @Mapping( target = "details.type", source = "detailsDTO.brand" )  // so this needs to be redone
+    Car map2(CarDTO in);
+
+    class Car {
+        //CHECKSTYLE:OFF
+        public float price;
+        public Details details;
+        //CHECKSTYLE:ON
+    }
+
+    class CarDTO {
+        //CHECKSTYLE:OFF
+        public float amount;
+        public DetailsDTO detailsDTO;
+        //CHECKSTYLE:ON
+    }
+
+    class Details {
+        //CHECKSTYLE:OFF
+        public String type;
+        public String id1;
+        public String id2;
+        //CHECKSTYLE:ON
+    }
+
+    class DetailsDTO {
+        //CHECKSTYLE:OFF
+        public String brand;
+        public String id1;
+        public String id2;
+        //CHECKSTYLE:ON
+    }
+
+}
diff --git a/processor/src/test/java/org/mapstruct/ap/test/bugs/_2278/Issue2278ReferenceMapper.java b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2278/Issue2278ReferenceMapper.java
new file mode 100644
index 000000000..48b457f84
--- /dev/null
+++ b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2278/Issue2278ReferenceMapper.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._2278;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.factory.Mappers;
+
+/**
+ * A reference mapper, that checks how a regular forward merge works
+ */
+@Mapper
+public interface Issue2278ReferenceMapper {
+
+    Issue2278ReferenceMapper INSTANCE = Mappers.getMapper( Issue2278ReferenceMapper.class );
+
+    @Mapping( target = "details", source = "detailsDTO" )
+    @Mapping( target = "details.model", ignore = true )
+    @Mapping( target = "details.type", constant = "gto")
+    @Mapping( target = "details.fuel", source = "detailsDTO.fuelType")
+    Car map(CarDTO in);
+
+    class Car {
+        //CHECKSTYLE:OFF
+        public Details details;
+        //CHECKSTYLE:ON
+    }
+
+    class CarDTO {
+        //CHECKSTYLE:OFF
+        public DetailsDTO detailsDTO;
+        //CHECKSTYLE:ON
+    }
+
+    class Details {
+        //CHECKSTYLE:OFF
+        public String brand;
+        public String model;
+        public String type;
+        public String fuel;
+        //CHECKSTYLE:ON
+    }
+
+    class DetailsDTO {
+        //CHECKSTYLE:OFF
+        public String brand;
+        public String fuelType;
+        //CHECKSTYLE:ON
+    }
+
+}
diff --git a/processor/src/test/java/org/mapstruct/ap/test/bugs/_2278/Issue2278Test.java b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2278/Issue2278Test.java
new file mode 100644
index 000000000..eefebfa87
--- /dev/null
+++ b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2278/Issue2278Test.java
@@ -0,0 +1,95 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._2278;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mapstruct.ap.testutil.IssueKey;
+import org.mapstruct.ap.testutil.WithClasses;
+import org.mapstruct.ap.testutil.runner.AnnotationProcessorTestRunner;
+
+@IssueKey("2278")
+@RunWith( AnnotationProcessorTestRunner.class)
+public class Issue2278Test {
+
+    @Test
+    @WithClasses( Issue2278ReferenceMapper.class )
+    public void testReferenceMergeBehaviour() {
+
+        Issue2278ReferenceMapper.CarDTO dto = new Issue2278ReferenceMapper.CarDTO();
+        dto.detailsDTO = new Issue2278ReferenceMapper.DetailsDTO();
+        dto.detailsDTO.brand = "Ford";
+        dto.detailsDTO.fuelType = "petrol";
+
+        Issue2278ReferenceMapper.Car target = Issue2278ReferenceMapper.INSTANCE.map( dto );
+
+        assertThat( target ).isNotNull();
+        assertThat( target.details ).isNotNull();
+        assertThat( target.details.brand ).isEqualTo( "Ford" );
+        assertThat( target.details.model ).isNull();
+        assertThat( target.details.type ).isEqualTo( "gto" );
+        assertThat( target.details.fuel ).isEqualTo( "petrol" );
+
+    }
+
+    @Test
+    @WithClasses( Issue2278MapperA.class )
+    public void shouldBehaveJustAsTestReferenceMergeBehaviour() {
+
+        Issue2278MapperA.CarDTO dto = new Issue2278MapperA.CarDTO();
+        dto.detailsDTO = new Issue2278MapperA.DetailsDTO();
+        dto.detailsDTO.brand = "Ford";
+        dto.detailsDTO.fuelType = "petrol";
+
+        Issue2278MapperA.Car target = Issue2278MapperA.INSTANCE.map( dto );
+
+        assertThat( target ).isNotNull();
+        assertThat( target.details ).isNotNull();
+        assertThat( target.details.brand ).isEqualTo( "Ford" );
+        assertThat( target.details.model ).isNull();
+        assertThat( target.details.type ).isEqualTo( "gto" );
+        assertThat( target.details.fuel ).isEqualTo( "petrol" );
+
+    }
+
+    @Test
+    @WithClasses( Issue2278MapperB.class )
+    public void shouldOverrideDetailsMappingWithRedefined() {
+
+        Issue2278MapperB.Car source = new Issue2278MapperB.Car();
+        source.details = new Issue2278MapperB.Details();
+        source.details.type = "Ford";
+        source.details.id1 = "id1";
+        source.details.id2 = "id2";
+        source.price = 20000f;
+
+        Issue2278MapperB.CarDTO target1 = Issue2278MapperB.INSTANCE.map( source );
+
+        assertThat( target1 ).isNotNull();
+        assertThat( target1.amount ).isEqualTo( 20000f );
+        assertThat( target1.detailsDTO ).isNotNull();
+        assertThat( target1.detailsDTO.brand ).isEqualTo( "Ford" );
+        assertThat( target1.detailsDTO.id1 ).isEqualTo( "id2" );
+        assertThat( target1.detailsDTO.id2 ).isEqualTo( "id1" );
+
+        // restore the mappings, just to make it logical again
+        target1.detailsDTO.id1 = "id1";
+        target1.detailsDTO.id2 = "id2";
+
+        // now check the reverse inheritance
+        Issue2278MapperB.Car target2 = Issue2278MapperB.INSTANCE.map2( target1 );
+
+        assertThat( target2 ).isNotNull();
+        assertThat( target2.price ).isEqualTo( 20000f );
+        assertThat( target2.details ).isNotNull();
+        assertThat( target2.details.type ).isEqualTo( "Ford" ); // should inherit
+        assertThat( target2.details.id1 ).isEqualTo( "id1" ); // should be undone
+        assertThat( target2.details.id2 ).isEqualTo( "id2" ); // should be undone
+    }
+
+}
diff --git a/processor/src/test/java/org/mapstruct/ap/test/bugs/_2318/Issue2318Mapper.java b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2318/Issue2318Mapper.java
new file mode 100644
index 000000000..20621e4d0
--- /dev/null
+++ b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2318/Issue2318Mapper.java
@@ -0,0 +1,115 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._2318;
+
+import org.mapstruct.InheritConfiguration;
+import org.mapstruct.Mapper;
+import org.mapstruct.MapperConfig;
+import org.mapstruct.Mapping;
+import org.mapstruct.factory.Mappers;
+
+@Mapper(config = Issue2318Mapper.Config.class)
+public interface Issue2318Mapper {
+
+    Issue2318Mapper INSTANCE = Mappers.getMapper( Issue2318Mapper.class );
+
+    @MapperConfig
+    interface Config {
+
+        @Mapping(target = "parentValue1", source = "holder")
+        TargetParent mapParent(SourceParent parent);
+
+        @InheritConfiguration(name = "mapParent")
+        @Mapping(target = "childValue", source = "value")
+        @Mapping(target = "parentValue2", source = "holder.parentValue2")
+        TargetChild mapChild(SourceChild child);
+    }
+
+    @InheritConfiguration(name = "mapChild")
+    TargetChild mapChild(SourceChild child);
+
+    default String parentValue1(SourceParent.Holder holder) {
+        return holder.getParentValue1();
+    }
+
+    class SourceParent {
+        private Holder holder;
+
+        public Holder getHolder() {
+            return holder;
+        }
+
+        public void setHolder(Holder holder) {
+            this.holder = holder;
+        }
+
+        public static class Holder {
+            private String parentValue1;
+            private Integer parentValue2;
+
+            public String getParentValue1() {
+                return parentValue1;
+            }
+
+            public void setParentValue1(String parentValue1) {
+                this.parentValue1 = parentValue1;
+            }
+
+            public Integer getParentValue2() {
+                return parentValue2;
+            }
+
+            public void setParentValue2(Integer parentValue2) {
+                this.parentValue2 = parentValue2;
+            }
+        }
+    }
+
+    class SourceChild extends SourceParent {
+        private String value;
+
+        public String getValue() {
+            return value;
+        }
+
+        public void setValue(String value) {
+            this.value = value;
+        }
+    }
+
+    class TargetParent {
+        private String parentValue1;
+        private Integer parentValue2;
+
+        public String getParentValue1() {
+            return parentValue1;
+        }
+
+        public void setParentValue1(String parentValue1) {
+            this.parentValue1 = parentValue1;
+        }
+
+        public Integer getParentValue2() {
+            return parentValue2;
+        }
+
+        public void setParentValue2(Integer parentValue2) {
+            this.parentValue2 = parentValue2;
+        }
+    }
+
+    class TargetChild extends TargetParent {
+        private String childValue;
+
+        public String getChildValue() {
+            return childValue;
+        }
+
+        public void setChildValue(String childValue) {
+            this.childValue = childValue;
+        }
+    }
+}
diff --git a/processor/src/test/java/org/mapstruct/ap/test/bugs/_2318/Issue2318Test.java b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2318/Issue2318Test.java
new file mode 100644
index 000000000..a1f1ad250
--- /dev/null
+++ b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2318/Issue2318Test.java
@@ -0,0 +1,38 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._2318;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mapstruct.ap.test.bugs._2318.Issue2318Mapper.SourceChild;
+import org.mapstruct.ap.test.bugs._2318.Issue2318Mapper.TargetChild;
+import org.mapstruct.ap.testutil.IssueKey;
+import org.mapstruct.ap.testutil.WithClasses;
+import org.mapstruct.ap.testutil.runner.AnnotationProcessorTestRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@IssueKey("2318")
+@RunWith(AnnotationProcessorTestRunner.class)
+public class Issue2318Test {
+
+    @Test
+    @WithClasses( Issue2318Mapper.class )
+    public void shouldMap() {
+
+        SourceChild source = new SourceChild();
+        source.setValue( "From child" );
+        source.setHolder( new Issue2318Mapper.SourceParent.Holder() );
+        source.getHolder().setParentValue1( "From parent" );
+        source.getHolder().setParentValue2( 12 );
+
+        TargetChild target = Issue2318Mapper.INSTANCE.mapChild( source );
+
+        assertThat( target.getParentValue1() ).isEqualTo( "From parent" );
+        assertThat( target.getParentValue2() ).isEqualTo( 12 );
+        assertThat( target.getChildValue() ).isEqualTo( "From child" );
+    }
+}