diff --git a/modules/openapi-generator/src/main/resources/C-libcurl/model-body.mustache b/modules/openapi-generator/src/main/resources/C-libcurl/model-body.mustache
index 493db3024f78..0f9ec305c74c 100644
--- a/modules/openapi-generator/src/main/resources/C-libcurl/model-body.mustache
+++ b/modules/openapi-generator/src/main/resources/C-libcurl/model-body.mustache
@@ -214,59 +214,92 @@ void {{classname}}_free({{classname}}_t *{{classname}}) {
     {{^isPrimitiveType}}
     {{#isModel}}
     {{^isEnum}}
-    {{{complexType}}}_free({{{classname}}}->{{{name}}});
+    if ({{{classname}}}->{{{name}}}) {
+        {{{complexType}}}_free({{{classname}}}->{{{name}}});
+        {{classname}}->{{name}} = NULL;
+    }
     {{/isEnum}}
     {{/isModel}}
     {{#isUuid}}
-    free({{{classname}}}->{{{name}}});
+    if ({{{classname}}}->{{{name}}}) {
+        free({{{classname}}}->{{{name}}});
+        {{classname}}->{{name}} = NULL;
+    }
     {{/isUuid}}
     {{#isEmail}}
-    free({{{classname}}}->{{{name}}});
+    if ({{{classname}}}->{{{name}}}) {
+        free({{{classname}}}->{{{name}}});
+        {{classname}}->{{name}} = NULL;
+    }
     {{/isEmail}}
     {{#isFreeFormObject}}
-    object_free({{{classname}}}->{{{name}}});
+    if ({{{classname}}}->{{{name}}}) {
+        object_free({{{classname}}}->{{{name}}});
+        {{classname}}->{{name}} = NULL;
+    }
     {{/isFreeFormObject}}
     {{/isPrimitiveType}}
     {{#isPrimitiveType}}
     {{^isEnum}}
     {{#isString}}
-    free({{{classname}}}->{{{name}}});
+    if ({{{classname}}}->{{{name}}}) {
+        free({{{classname}}}->{{{name}}});
+        {{classname}}->{{name}} = NULL;
+    }
     {{/isString}}
     {{/isEnum}}
     {{#isBinary}}
-    free({{{classname}}}->{{{name}}}->data);
+    if ({{{classname}}}->{{{name}}}) {
+        free({{{classname}}}->{{{name}}}->data);
+        {{classname}}->{{name}} = NULL;
+    }
     {{/isBinary}}
     {{#isDate}}
-    free({{{classname}}}->{{{name}}});
+    if ({{{classname}}}->{{{name}}}) {
+        free({{{classname}}}->{{{name}}});
+        {{classname}}->{{name}} = NULL;
+    }
     {{/isDate}}
     {{#isDateTime}}
-    free({{{classname}}}->{{{name}}});
+    if ({{{classname}}}->{{{name}}}) {
+        free({{{classname}}}->{{{name}}});
+        {{classname}}->{{name}} = NULL;
+    }
     {{/isDateTime}}
     {{/isPrimitiveType}}
     {{/isContainer}}
     {{#isContainer}}
     {{#isArray}}
     {{#isPrimitiveType}}
-    list_ForEach(listEntry, {{classname}}->{{name}}) {
-        free(listEntry->data);
+    if ({{{classname}}}->{{{name}}}) {
+        list_ForEach(listEntry, {{classname}}->{{name}}) {
+            free(listEntry->data);
+        }
+        list_free({{classname}}->{{name}});
+        {{classname}}->{{name}} = NULL;
     }
-    list_free({{classname}}->{{name}});
     {{/isPrimitiveType}}
     {{^isPrimitiveType}}
-    list_ForEach(listEntry, {{classname}}->{{name}}) {
-        {{complexType}}_free(listEntry->data);
+    if ({{{classname}}}->{{{name}}}) {
+        list_ForEach(listEntry, {{classname}}->{{name}}) {
+            {{complexType}}_free(listEntry->data);
+        }
+        list_free({{classname}}->{{name}});
+        {{classname}}->{{name}} = NULL;
     }
-    list_free({{classname}}->{{name}});
     {{/isPrimitiveType}}
     {{/isArray}}
     {{#isMap}}
-    list_ForEach(listEntry, {{classname}}->{{name}}) {
-        keyValuePair_t *localKeyValue = (keyValuePair_t*) listEntry->data;
-        free (localKeyValue->key);
-        free (localKeyValue->value);
-        keyValuePair_free(localKeyValue);
+    if ({{{classname}}}->{{{name}}}) {
+        list_ForEach(listEntry, {{classname}}->{{name}}) {
+            keyValuePair_t *localKeyValue = (keyValuePair_t*) listEntry->data;
+            free (localKeyValue->key);
+            free (localKeyValue->value);
+            keyValuePair_free(localKeyValue);
+        }
+        list_free({{classname}}->{{name}});
+        {{classname}}->{{name}} = NULL;
     }
-    list_free({{classname}}->{{name}});
     {{/isMap}}
     {{/isContainer}}
     {{/vars}}
diff --git a/samples/client/petstore/c/model/api_response.c b/samples/client/petstore/c/model/api_response.c
index 9cb2b1ddd8b7..f783fd848545 100644
--- a/samples/client/petstore/c/model/api_response.c
+++ b/samples/client/petstore/c/model/api_response.c
@@ -27,8 +27,14 @@ void api_response_free(api_response_t *api_response) {
         return ;
     }
     listEntry_t *listEntry;
-    free(api_response->type);
-    free(api_response->message);
+    if (api_response->type) {
+        free(api_response->type);
+        api_response->type = NULL;
+    }
+    if (api_response->message) {
+        free(api_response->message);
+        api_response->message = NULL;
+    }
     free(api_response);
 }
 
diff --git a/samples/client/petstore/c/model/category.c b/samples/client/petstore/c/model/category.c
index 8aa29c042279..c192b2b96058 100644
--- a/samples/client/petstore/c/model/category.c
+++ b/samples/client/petstore/c/model/category.c
@@ -25,7 +25,10 @@ void category_free(category_t *category) {
         return ;
     }
     listEntry_t *listEntry;
-    free(category->name);
+    if (category->name) {
+        free(category->name);
+        category->name = NULL;
+    }
     free(category);
 }
 
diff --git a/samples/client/petstore/c/model/order.c b/samples/client/petstore/c/model/order.c
index fb6367339fd9..f9e518452738 100644
--- a/samples/client/petstore/c/model/order.c
+++ b/samples/client/petstore/c/model/order.c
@@ -50,7 +50,10 @@ void order_free(order_t *order) {
         return ;
     }
     listEntry_t *listEntry;
-    free(order->ship_date);
+    if (order->ship_date) {
+        free(order->ship_date);
+        order->ship_date = NULL;
+    }
     free(order);
 }
 
diff --git a/samples/client/petstore/c/model/pet.c b/samples/client/petstore/c/model/pet.c
index f2c4b81806ed..8acdcfa132e7 100644
--- a/samples/client/petstore/c/model/pet.c
+++ b/samples/client/petstore/c/model/pet.c
@@ -50,16 +50,28 @@ void pet_free(pet_t *pet) {
         return ;
     }
     listEntry_t *listEntry;
-    category_free(pet->category);
-    free(pet->name);
-    list_ForEach(listEntry, pet->photo_urls) {
-        free(listEntry->data);
+    if (pet->category) {
+        category_free(pet->category);
+        pet->category = NULL;
     }
-    list_free(pet->photo_urls);
-    list_ForEach(listEntry, pet->tags) {
-        tag_free(listEntry->data);
+    if (pet->name) {
+        free(pet->name);
+        pet->name = NULL;
+    }
+    if (pet->photo_urls) {
+        list_ForEach(listEntry, pet->photo_urls) {
+            free(listEntry->data);
+        }
+        list_free(pet->photo_urls);
+        pet->photo_urls = NULL;
+    }
+    if (pet->tags) {
+        list_ForEach(listEntry, pet->tags) {
+            tag_free(listEntry->data);
+        }
+        list_free(pet->tags);
+        pet->tags = NULL;
     }
-    list_free(pet->tags);
     free(pet);
 }
 
diff --git a/samples/client/petstore/c/model/tag.c b/samples/client/petstore/c/model/tag.c
index cbfba498aced..00b62ddb0764 100644
--- a/samples/client/petstore/c/model/tag.c
+++ b/samples/client/petstore/c/model/tag.c
@@ -25,7 +25,10 @@ void tag_free(tag_t *tag) {
         return ;
     }
     listEntry_t *listEntry;
-    free(tag->name);
+    if (tag->name) {
+        free(tag->name);
+        tag->name = NULL;
+    }
     free(tag);
 }
 
diff --git a/samples/client/petstore/c/model/user.c b/samples/client/petstore/c/model/user.c
index da6846cc3dbc..eab6606225d4 100644
--- a/samples/client/petstore/c/model/user.c
+++ b/samples/client/petstore/c/model/user.c
@@ -37,12 +37,30 @@ void user_free(user_t *user) {
         return ;
     }
     listEntry_t *listEntry;
-    free(user->username);
-    free(user->first_name);
-    free(user->last_name);
-    free(user->email);
-    free(user->password);
-    free(user->phone);
+    if (user->username) {
+        free(user->username);
+        user->username = NULL;
+    }
+    if (user->first_name) {
+        free(user->first_name);
+        user->first_name = NULL;
+    }
+    if (user->last_name) {
+        free(user->last_name);
+        user->last_name = NULL;
+    }
+    if (user->email) {
+        free(user->email);
+        user->email = NULL;
+    }
+    if (user->password) {
+        free(user->password);
+        user->password = NULL;
+    }
+    if (user->phone) {
+        free(user->phone);
+        user->phone = NULL;
+    }
     free(user);
 }