diff --git a/modules/openapi-generator/src/main/resources/go/api.mustache b/modules/openapi-generator/src/main/resources/go/api.mustache
index b3dd0df695c..3e9ff07a7b2 100644
--- a/modules/openapi-generator/src/main/resources/go/api.mustache
+++ b/modules/openapi-generator/src/main/resources/go/api.mustache
@@ -216,7 +216,10 @@ func (a *{{{classname}}}Service) {{nickname}}Execute(r {{#structPrefix}}{{&class
 	{{^isCollectionFormatMulti}}
 		parameterAddToHeaderOrQuery(localVarQueryParams, "{{baseName}}", r.{{paramName}}, "{{collectionFormat}}")
 	{{/isCollectionFormatMulti}}
-	}
+	{{#defaultValue}}} else {
+		var defaultValue {{{dataType}}} = {{{.}}}
+		r.{{paramName}} = &defaultValue
+	{{/defaultValue}}}
 	{{/required}}
 	{{/queryParams}}
 	// to determine the Content-Type header
diff --git a/samples/client/petstore/go/go-petstore/api_fake.go b/samples/client/petstore/go/go-petstore/api_fake.go
index 7a1031f4770..b03ecad8937 100644
--- a/samples/client/petstore/go/go-petstore/api_fake.go
+++ b/samples/client/petstore/go/go-petstore/api_fake.go
@@ -1426,6 +1426,9 @@ func (a *FakeAPIService) TestEnumParametersExecute(r ApiTestEnumParametersReques
 	}
 	if r.enumQueryString != nil {
 		parameterAddToHeaderOrQuery(localVarQueryParams, "enum_query_string", r.enumQueryString, "")
+	} else {
+		var defaultValue string = "-efg"
+		r.enumQueryString = &defaultValue
 	}
 	if r.enumQueryInteger != nil {
 		parameterAddToHeaderOrQuery(localVarQueryParams, "enum_query_integer", r.enumQueryInteger, "")
diff --git a/samples/openapi3/client/petstore/go/go-petstore/api_fake.go b/samples/openapi3/client/petstore/go/go-petstore/api_fake.go
index e2757fd779c..4b36fb36c75 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/api_fake.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/api_fake.go
@@ -1602,6 +1602,9 @@ func (a *FakeAPIService) TestEnumParametersExecute(r ApiTestEnumParametersReques
 	}
 	if r.enumQueryString != nil {
 		parameterAddToHeaderOrQuery(localVarQueryParams, "enum_query_string", r.enumQueryString, "")
+	} else {
+		var defaultValue string = "-efg"
+		r.enumQueryString = &defaultValue
 	}
 	if r.enumQueryInteger != nil {
 		parameterAddToHeaderOrQuery(localVarQueryParams, "enum_query_integer", r.enumQueryInteger, "")