diff --git a/src/main/java/com/kobylynskyi/graphql/codegen/mapper/AnnotationsMapper.java b/src/main/java/com/kobylynskyi/graphql/codegen/mapper/AnnotationsMapper.java
index ecc6a103e..fbfb2453f 100644
--- a/src/main/java/com/kobylynskyi/graphql/codegen/mapper/AnnotationsMapper.java
+++ b/src/main/java/com/kobylynskyi/graphql/codegen/mapper/AnnotationsMapper.java
@@ -8,6 +8,7 @@
 import graphql.language.Argument;
 import graphql.language.Directive;
 import graphql.language.InputValueDefinition;
+import graphql.language.InterfaceTypeDefinition;
 import graphql.language.ListType;
 import graphql.language.NamedNode;
 import graphql.language.NonNullType;
@@ -204,7 +205,7 @@ public List<String> getAnnotationsForDirective(MappingContext mappingContext,
     public List<String> getJacksonTypeIdAnnotations(MappingContext mappingContext, NamedNode<?> def) {
         List<String> defaults = new ArrayList<>();
         if (Boolean.TRUE.equals(mappingContext.getGenerateJacksonTypeIdResolver())
-                && def instanceof UnionTypeDefinition) {
+                && (def instanceof UnionTypeDefinition || def instanceof InterfaceTypeDefinition)) {
             defaults.add("com.fasterxml.jackson.annotation.JsonTypeInfo(use = " +
                     "com.fasterxml.jackson.annotation.JsonTypeInfo.Id.NAME, property = \"__typename\")");
             String modelPackageName = DataModelMapper.getModelPackageName(mappingContext);
diff --git a/src/test/java/com/kobylynskyi/graphql/codegen/GraphQLCodegenTest.java b/src/test/java/com/kobylynskyi/graphql/codegen/GraphQLCodegenTest.java
index bce94a841..ce083407f 100644
--- a/src/test/java/com/kobylynskyi/graphql/codegen/GraphQLCodegenTest.java
+++ b/src/test/java/com/kobylynskyi/graphql/codegen/GraphQLCodegenTest.java
@@ -21,6 +21,7 @@
 import static com.kobylynskyi.graphql.codegen.TestUtils.assertFileContainsElements;
 import static com.kobylynskyi.graphql.codegen.TestUtils.assertSameTrimmedContent;
 import static com.kobylynskyi.graphql.codegen.TestUtils.getFileByName;
+import static java.lang.System.lineSeparator;
 import static java.util.Collections.emptyList;
 import static java.util.Collections.singletonList;
 import static java.util.Collections.singletonMap;
@@ -141,11 +142,10 @@ void generate_NoPackage() throws Exception {
         generate("src/test/resources/schemas/test.graphqls");
 
         File[] files = Objects.requireNonNull(outputBuildDir.listFiles());
-        assertFileContainsElements(files, "Event.java", System.lineSeparator() +
-                "/**" + System.lineSeparator() +
-                " * An event that describes a thing that happens" + System
-                .lineSeparator() +
-                " */" + System.lineSeparator());
+        assertFileContainsElements(files, "Event.java", lineSeparator() +
+                "/**" + lineSeparator() +
+                " * An event that describes a thing that happens" + lineSeparator() +
+                " */" + lineSeparator());
     }
 
     @Test
diff --git a/src/test/resources/expected-classes/jackson-resolver-union/ResultObject.java.txt b/src/test/resources/expected-classes/jackson-resolver-union/ResultObject.java.txt
index a4aa0ed2d..ccaceef42 100644
--- a/src/test/resources/expected-classes/jackson-resolver-union/ResultObject.java.txt
+++ b/src/test/resources/expected-classes/jackson-resolver-union/ResultObject.java.txt
@@ -5,8 +5,10 @@ package com.kobylynskyi.graphql.unionresolver;
     value = "com.kobylynskyi.graphql.codegen.GraphQLCodegen",
     date = "2020-12-31T23:59:59-0500"
 )
+@com.fasterxml.jackson.annotation.JsonTypeInfo(use = com.fasterxml.jackson.annotation.JsonTypeInfo.Id.NAME, property = "__typename")
+@com.fasterxml.jackson.databind.annotation.JsonTypeIdResolver(com.kobylynskyi.graphql.unionresolver.GraphqlJacksonTypeIdResolver.class)
 public interface ResultObject {
 
     java.util.List<? extends UnionToResolve> getList();
 
-}
\ No newline at end of file
+}
diff --git a/src/test/resources/expected-classes/jackson-resolver-union/without-model-package/MyResultObjectSuffix.java.txt b/src/test/resources/expected-classes/jackson-resolver-union/without-model-package/MyResultObjectSuffix.java.txt
index 2ee4011e0..4acd42053 100644
--- a/src/test/resources/expected-classes/jackson-resolver-union/without-model-package/MyResultObjectSuffix.java.txt
+++ b/src/test/resources/expected-classes/jackson-resolver-union/without-model-package/MyResultObjectSuffix.java.txt
@@ -2,8 +2,10 @@
     value = "com.kobylynskyi.graphql.codegen.GraphQLCodegen",
     date = "2020-12-31T23:59:59-0500"
 )
+@com.fasterxml.jackson.annotation.JsonTypeInfo(use = com.fasterxml.jackson.annotation.JsonTypeInfo.Id.NAME, property = "__typename")
+@com.fasterxml.jackson.databind.annotation.JsonTypeIdResolver(GraphqlJacksonTypeIdResolver.class)
 public interface MyResultObjectSuffix {
 
     java.util.List<? extends MyUnionToResolveSuffix> getList();
 
-}
\ No newline at end of file
+}
diff --git a/src/test/resources/expected-classes/kt/jackson-resolver-union/ResultObject.kt.txt b/src/test/resources/expected-classes/kt/jackson-resolver-union/ResultObject.kt.txt
index e09549ab7..ce3847886 100644
--- a/src/test/resources/expected-classes/kt/jackson-resolver-union/ResultObject.kt.txt
+++ b/src/test/resources/expected-classes/kt/jackson-resolver-union/ResultObject.kt.txt
@@ -5,8 +5,10 @@ package com.kobylynskyi.graphql.unionresolver
     value = ["com.kobylynskyi.graphql.codegen.GraphQLCodegen"],
     date = "2020-12-31T23:59:59-0500"
 )
+@com.fasterxml.jackson.annotation.JsonTypeInfo(use = com.fasterxml.jackson.annotation.JsonTypeInfo.Id.NAME, property = "__typename")
+@com.fasterxml.jackson.databind.annotation.JsonTypeIdResolver(com.kobylynskyi.graphql.unionresolver.GraphqlJacksonTypeIdResolver::class)
 interface ResultObject {
 
     val list: List<out UnionToResolve>?
 
-}
\ No newline at end of file
+}
diff --git a/src/test/resources/expected-classes/kt/jackson-resolver-union/without-model-package/MyResultObjectSuffix.kt.txt b/src/test/resources/expected-classes/kt/jackson-resolver-union/without-model-package/MyResultObjectSuffix.kt.txt
index 71f2ad729..a4a619cca 100644
--- a/src/test/resources/expected-classes/kt/jackson-resolver-union/without-model-package/MyResultObjectSuffix.kt.txt
+++ b/src/test/resources/expected-classes/kt/jackson-resolver-union/without-model-package/MyResultObjectSuffix.kt.txt
@@ -2,8 +2,10 @@
     value = ["com.kobylynskyi.graphql.codegen.GraphQLCodegen"],
     date = "2020-12-31T23:59:59-0500"
 )
+@com.fasterxml.jackson.annotation.JsonTypeInfo(use = com.fasterxml.jackson.annotation.JsonTypeInfo.Id.NAME, property = "__typename")
+@com.fasterxml.jackson.databind.annotation.JsonTypeIdResolver(GraphqlJacksonTypeIdResolver::class)
 interface MyResultObjectSuffix {
 
     val list: List<out MyUnionToResolveSuffix>?
 
-}
\ No newline at end of file
+}
diff --git a/src/test/resources/expected-classes/scala/jackson-resolver-union/ResultObject.scala.txt b/src/test/resources/expected-classes/scala/jackson-resolver-union/ResultObject.scala.txt
index f9ad137de..7cc67ab11 100644
--- a/src/test/resources/expected-classes/scala/jackson-resolver-union/ResultObject.scala.txt
+++ b/src/test/resources/expected-classes/scala/jackson-resolver-union/ResultObject.scala.txt
@@ -5,8 +5,10 @@ package com.kobylynskyi.graphql.unionresolver
     value = Array("com.kobylynskyi.graphql.codegen.GraphQLCodegen"),
     date = "2020-12-31T23:59:59-0500"
 )
+@com.fasterxml.jackson.annotation.JsonTypeInfo(use = com.fasterxml.jackson.annotation.JsonTypeInfo.Id.NAME, property = "__typename")
+@com.fasterxml.jackson.databind.annotation.JsonTypeIdResolver(classOf[com.kobylynskyi.graphql.unionresolver.GraphqlJacksonTypeIdResolver])
 trait ResultObject {
 
     val list: scala.Seq[_ <: UnionToResolve]
 
-}
\ No newline at end of file
+}
diff --git a/src/test/resources/expected-classes/scala/jackson-resolver-union/without-model-package/MyResultObjectSuffix.scala.txt b/src/test/resources/expected-classes/scala/jackson-resolver-union/without-model-package/MyResultObjectSuffix.scala.txt
index 19d9d82d5..b921de8d0 100644
--- a/src/test/resources/expected-classes/scala/jackson-resolver-union/without-model-package/MyResultObjectSuffix.scala.txt
+++ b/src/test/resources/expected-classes/scala/jackson-resolver-union/without-model-package/MyResultObjectSuffix.scala.txt
@@ -2,8 +2,10 @@
     value = Array("com.kobylynskyi.graphql.codegen.GraphQLCodegen"),
     date = "2020-12-31T23:59:59-0500"
 )
+@com.fasterxml.jackson.annotation.JsonTypeInfo(use = com.fasterxml.jackson.annotation.JsonTypeInfo.Id.NAME, property = "__typename")
+@com.fasterxml.jackson.databind.annotation.JsonTypeIdResolver(classOf[GraphqlJacksonTypeIdResolver])
 trait MyResultObjectSuffix {
 
     val list: scala.Seq[_ <: MyUnionToResolveSuffix]
 
-}
\ No newline at end of file
+}