diff --git a/modules/openapi-generator/src/main/resources/typescript-angular/configuration.mustache b/modules/openapi-generator/src/main/resources/typescript-angular/configuration.mustache
index e73eeebf7b6..39f73f8e2a5 100644
--- a/modules/openapi-generator/src/main/resources/typescript-angular/configuration.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-angular/configuration.mustache
@@ -196,7 +196,7 @@ export class {{configurationClassName}} {
         //
         // But: if that's all you need (i.e.: the most common use-case): no need for customization!
 
-        const value = param.dataFormat === 'date-time'
+        const value = param.dataFormat === 'date-time' && param.value instanceof Date
             ? (param.value as Date).toISOString()
             : param.value;
 
diff --git a/modules/openapi-generator/src/test/resources/integrationtests/typescript/additional-properties-expected/configuration.ts b/modules/openapi-generator/src/test/resources/integrationtests/typescript/additional-properties-expected/configuration.ts
index d38a4c153f2..526b454fb2b 100644
--- a/modules/openapi-generator/src/test/resources/integrationtests/typescript/additional-properties-expected/configuration.ts
+++ b/modules/openapi-generator/src/test/resources/integrationtests/typescript/additional-properties-expected/configuration.ts
@@ -157,7 +157,7 @@ export class Configuration {
         //
         // But: if that's all you need (i.e.: the most common use-case): no need for customization!
 
-        const value = param.dataFormat === 'date-time'
+        const value = param.dataFormat === 'date-time' && param.value instanceof Date
             ? (param.value as Date).toISOString()
             : param.value;
 
diff --git a/modules/openapi-generator/src/test/resources/integrationtests/typescript/array-and-object-expected/configuration.ts b/modules/openapi-generator/src/test/resources/integrationtests/typescript/array-and-object-expected/configuration.ts
index d38a4c153f2..526b454fb2b 100644
--- a/modules/openapi-generator/src/test/resources/integrationtests/typescript/array-and-object-expected/configuration.ts
+++ b/modules/openapi-generator/src/test/resources/integrationtests/typescript/array-and-object-expected/configuration.ts
@@ -157,7 +157,7 @@ export class Configuration {
         //
         // But: if that's all you need (i.e.: the most common use-case): no need for customization!
 
-        const value = param.dataFormat === 'date-time'
+        const value = param.dataFormat === 'date-time' && param.value instanceof Date
             ? (param.value as Date).toISOString()
             : param.value;
 
diff --git a/modules/openapi-generator/src/test/resources/integrationtests/typescript/custom-path-params-expected/configuration.ts b/modules/openapi-generator/src/test/resources/integrationtests/typescript/custom-path-params-expected/configuration.ts
index d38a4c153f2..526b454fb2b 100644
--- a/modules/openapi-generator/src/test/resources/integrationtests/typescript/custom-path-params-expected/configuration.ts
+++ b/modules/openapi-generator/src/test/resources/integrationtests/typescript/custom-path-params-expected/configuration.ts
@@ -157,7 +157,7 @@ export class Configuration {
         //
         // But: if that's all you need (i.e.: the most common use-case): no need for customization!
 
-        const value = param.dataFormat === 'date-time'
+        const value = param.dataFormat === 'date-time' && param.value instanceof Date
             ? (param.value as Date).toISOString()
             : param.value;
 
diff --git a/modules/openapi-generator/src/test/resources/integrationtests/typescript/petstore-expected/configuration.ts b/modules/openapi-generator/src/test/resources/integrationtests/typescript/petstore-expected/configuration.ts
index 5ea92c82cb6..c119def95af 100644
--- a/modules/openapi-generator/src/test/resources/integrationtests/typescript/petstore-expected/configuration.ts
+++ b/modules/openapi-generator/src/test/resources/integrationtests/typescript/petstore-expected/configuration.ts
@@ -177,7 +177,7 @@ export class Configuration {
         //
         // But: if that's all you need (i.e.: the most common use-case): no need for customization!
 
-        const value = param.dataFormat === 'date-time'
+        const value = param.dataFormat === 'date-time' && param.value instanceof Date
             ? (param.value as Date).toISOString()
             : param.value;
 
diff --git a/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/configuration.ts
index d38a4c153f2..526b454fb2b 100644
--- a/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/configuration.ts
@@ -157,7 +157,7 @@ export class Configuration {
         //
         // But: if that's all you need (i.e.: the most common use-case): no need for customization!
 
-        const value = param.dataFormat === 'date-time'
+        const value = param.dataFormat === 'date-time' && param.value instanceof Date
             ? (param.value as Date).toISOString()
             : param.value;
 
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/configuration.ts
index 5ea92c82cb6..c119def95af 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/configuration.ts
@@ -177,7 +177,7 @@ export class Configuration {
         //
         // But: if that's all you need (i.e.: the most common use-case): no need for customization!
 
-        const value = param.dataFormat === 'date-time'
+        const value = param.dataFormat === 'date-time' && param.value instanceof Date
             ? (param.value as Date).toISOString()
             : param.value;
 
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/configuration.ts
index 5ea92c82cb6..c119def95af 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/configuration.ts
@@ -177,7 +177,7 @@ export class Configuration {
         //
         // But: if that's all you need (i.e.: the most common use-case): no need for customization!
 
-        const value = param.dataFormat === 'date-time'
+        const value = param.dataFormat === 'date-time' && param.value instanceof Date
             ? (param.value as Date).toISOString()
             : param.value;
 
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/configuration.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/configuration.ts
index 5ea92c82cb6..c119def95af 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/configuration.ts
@@ -177,7 +177,7 @@ export class Configuration {
         //
         // But: if that's all you need (i.e.: the most common use-case): no need for customization!
 
-        const value = param.dataFormat === 'date-time'
+        const value = param.dataFormat === 'date-time' && param.value instanceof Date
             ? (param.value as Date).toISOString()
             : param.value;
 
diff --git a/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/configuration.ts
index d38a4c153f2..526b454fb2b 100644
--- a/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/configuration.ts
@@ -157,7 +157,7 @@ export class Configuration {
         //
         // But: if that's all you need (i.e.: the most common use-case): no need for customization!
 
-        const value = param.dataFormat === 'date-time'
+        const value = param.dataFormat === 'date-time' && param.value instanceof Date
             ? (param.value as Date).toISOString()
             : param.value;
 
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/configuration.ts
index 5ea92c82cb6..c119def95af 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/configuration.ts
@@ -177,7 +177,7 @@ export class Configuration {
         //
         // But: if that's all you need (i.e.: the most common use-case): no need for customization!
 
-        const value = param.dataFormat === 'date-time'
+        const value = param.dataFormat === 'date-time' && param.value instanceof Date
             ? (param.value as Date).toISOString()
             : param.value;
 
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/configuration.ts
index 5ea92c82cb6..c119def95af 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/configuration.ts
@@ -177,7 +177,7 @@ export class Configuration {
         //
         // But: if that's all you need (i.e.: the most common use-case): no need for customization!
 
-        const value = param.dataFormat === 'date-time'
+        const value = param.dataFormat === 'date-time' && param.value instanceof Date
             ? (param.value as Date).toISOString()
             : param.value;
 
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/configuration.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/configuration.ts
index 5ea92c82cb6..c119def95af 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/configuration.ts
@@ -177,7 +177,7 @@ export class Configuration {
         //
         // But: if that's all you need (i.e.: the most common use-case): no need for customization!
 
-        const value = param.dataFormat === 'date-time'
+        const value = param.dataFormat === 'date-time' && param.value instanceof Date
             ? (param.value as Date).toISOString()
             : param.value;
 
diff --git a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/configuration.ts
index 5ea92c82cb6..c119def95af 100644
--- a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/configuration.ts
@@ -177,7 +177,7 @@ export class Configuration {
         //
         // But: if that's all you need (i.e.: the most common use-case): no need for customization!
 
-        const value = param.dataFormat === 'date-time'
+        const value = param.dataFormat === 'date-time' && param.value instanceof Date
             ? (param.value as Date).toISOString()
             : param.value;
 
diff --git a/samples/client/petstore/typescript-angular-v14-query-param-object-format/configuration.ts b/samples/client/petstore/typescript-angular-v14-query-param-object-format/configuration.ts
index 5ea92c82cb6..c119def95af 100644
--- a/samples/client/petstore/typescript-angular-v14-query-param-object-format/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v14-query-param-object-format/configuration.ts
@@ -177,7 +177,7 @@ export class Configuration {
         //
         // But: if that's all you need (i.e.: the most common use-case): no need for customization!
 
-        const value = param.dataFormat === 'date-time'
+        const value = param.dataFormat === 'date-time' && param.value instanceof Date
             ? (param.value as Date).toISOString()
             : param.value;