diff --git a/docs/generators/typescript-fetch.md b/docs/generators/typescript-fetch.md
index f548480236b8..bdd09c095250 100644
--- a/docs/generators/typescript-fetch.md
+++ b/docs/generators/typescript-fetch.md
@@ -37,7 +37,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |sortModelPropertiesByRequiredFlag|Sort model properties to place required parameters before optional parameters.| |true|
 |sortParamsByRequiredFlag|Sort method arguments to place required parameters before optional parameters.| |true|
 |supportsES6|Generate code that conforms to ES6.| |false|
-|typescriptThreePlus|Setting this property to true will generate TypeScript 3.6+ compatible code.| |false|
+|typescriptThreePlus|Setting this property to true will generate TypeScript 3.6+ compatible code.| |true|
 |useSingleRequestParameter|Setting this property to true will generate functions with a single argument containing all API endpoint parameters instead of one argument per parameter.| |true|
 |withInterfaces|Setting this property to true will generate interfaces next to the default class implementations.| |false|
 |withoutRuntimeChecks|Setting this property to true will remove any runtime checks on the request and response payloads. Payloads will be casted to their expected types.| |false|
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptFetchClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptFetchClientCodegen.java
index 5c810f7073b1..8924e3b0b62f 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptFetchClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptFetchClientCodegen.java
@@ -47,7 +47,7 @@ public class TypeScriptFetchClientCodegen extends AbstractTypeScriptClientCodege
     private boolean prefixParameterInterfaces = false;
     protected boolean addedApiIndex = false;
     protected boolean addedModelIndex = false;
-    protected boolean typescriptThreePlus = false;
+    protected boolean typescriptThreePlus = true;
     protected boolean withoutRuntimeChecks = false;
 
     // "Saga and Record" mode.
@@ -93,7 +93,7 @@ public TypeScriptFetchClientCodegen() {
         this.cliOptions.add(new CliOption(WITH_INTERFACES, "Setting this property to true will generate interfaces next to the default class implementations.", SchemaTypeUtil.BOOLEAN_TYPE).defaultValue(Boolean.FALSE.toString()));
         this.cliOptions.add(new CliOption(CodegenConstants.USE_SINGLE_REQUEST_PARAMETER, CodegenConstants.USE_SINGLE_REQUEST_PARAMETER_DESC, SchemaTypeUtil.BOOLEAN_TYPE).defaultValue(Boolean.TRUE.toString()));
         this.cliOptions.add(new CliOption(PREFIX_PARAMETER_INTERFACES, "Setting this property to true will generate parameter interface declarations prefixed with API class name to avoid name conflicts.", SchemaTypeUtil.BOOLEAN_TYPE).defaultValue(Boolean.FALSE.toString()));
-        this.cliOptions.add(new CliOption(TYPESCRIPT_THREE_PLUS, "Setting this property to true will generate TypeScript 3.6+ compatible code.", SchemaTypeUtil.BOOLEAN_TYPE).defaultValue(Boolean.FALSE.toString()));
+        this.cliOptions.add(new CliOption(TYPESCRIPT_THREE_PLUS, "Setting this property to true will generate TypeScript 3.6+ compatible code.", SchemaTypeUtil.BOOLEAN_TYPE).defaultValue(Boolean.TRUE.toString()));
         this.cliOptions.add(new CliOption(WITHOUT_RUNTIME_CHECKS, "Setting this property to true will remove any runtime checks on the request and response payloads. Payloads will be casted to their expected types.", SchemaTypeUtil.BOOLEAN_TYPE).defaultValue(Boolean.FALSE.toString()));
         this.cliOptions.add(new CliOption(SAGAS_AND_RECORDS, "Setting this property to true will generate additional files for use with redux-saga and immutablejs.", SchemaTypeUtil.BOOLEAN_TYPE).defaultValue(Boolean.FALSE.toString()));
     }