diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartDioNextClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartDioNextClientCodegen.java
index 5bc677623de..9acfe364003 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartDioNextClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartDioNextClientCodegen.java
@@ -420,6 +420,8 @@ public class DartDioNextClientCodegen extends AbstractDartCodegen {
                     continue;
                 }
                 resultImports.add(i);
+            } else if (importMapping().containsKey(modelImport)) {
+                resultImports.add(importMapping().get(modelImport));
             } else {
                 resultImports.add("package:" + pubName + "/src/model/" + underscore(modelImport) + ".dart");
             }
diff --git a/modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/built_value/class.mustache b/modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/built_value/class.mustache
index f77c8b91506..11bc668b902 100644
--- a/modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/built_value/class.mustache
+++ b/modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/built_value/class.mustache
@@ -105,7 +105,13 @@ class _${{classname}}Serializer implements StructuredSerializer<{{classname}}> {
                     result.{{{name}}}.replace(valueDes);
                     {{/isContainer}}
                     {{#isModel}}
+                    {{#isPrimitiveType}}
+                    {{! These are models that have nee manually marked as primitve via generator param. }}
+                    result.{{{name}}} = valueDes;
+                    {{/isPrimitiveType}}
+                    {{^isPrimitiveType}}
                     result.{{{name}}}.replace(valueDes);
+                    {{/isPrimitiveType}}
                     {{/isModel}}
                     {{^isContainer}}
                     {{^isModel}}