diff --git a/processor/src/test/java/org/mapstruct/ap/test/bugs/_2121/Issue2121Mapper.java b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2121/Issue2121Mapper.java
new file mode 100644
index 000000000..f61300c0e
--- /dev/null
+++ b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2121/Issue2121Mapper.java
@@ -0,0 +1,51 @@
+/*
+ * 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._2121;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.factory.Mappers;
+
+/**
+ * @author Filip Hrisafov
+ */
+@Mapper
+public interface Issue2121Mapper {
+
+    Issue2121Mapper INSTANCE = Mappers.getMapper( Issue2121Mapper.class );
+
+    Target map(Source source);
+
+    class Target {
+
+        private final String value;
+
+        public Target(String value) {
+            this.value = value;
+        }
+
+        public String getValue() {
+            return value;
+        }
+    }
+
+    class Source {
+
+        private final SourceEnum value;
+
+        public Source(SourceEnum value) {
+            this.value = value;
+        }
+
+        public SourceEnum getValue() {
+            return value;
+        }
+    }
+
+    enum SourceEnum {
+        VALUE1,
+        VALUE2
+    }
+}
diff --git a/processor/src/test/java/org/mapstruct/ap/test/bugs/_2121/Issue2121Test.java b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2121/Issue2121Test.java
new file mode 100644
index 000000000..3d6f6dfca
--- /dev/null
+++ b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2121/Issue2121Test.java
@@ -0,0 +1,36 @@
+/*
+ * 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._2121;
+
+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;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Filip Hrisafov
+ */
+@IssueKey("2121")
+@RunWith(AnnotationProcessorTestRunner.class)
+@WithClasses(Issue2121Mapper.class)
+public class Issue2121Test {
+
+    @Test
+    public void shouldCompile() {
+        Issue2121Mapper mapper = Issue2121Mapper.INSTANCE;
+
+        Issue2121Mapper.Target target = mapper.map( new Issue2121Mapper.Source( Issue2121Mapper.SourceEnum.VALUE1 ) );
+        assertThat( target ).isNotNull();
+        assertThat( target.getValue() ).isEqualTo( "VALUE1" );
+
+        target = mapper.map( new Issue2121Mapper.Source( null ) );
+        assertThat( target ).isNotNull();
+        assertThat( target.getValue() ).isNull();
+    }
+}