diff --git a/samples/client/others/c/bearerAuth/CMakeLists.txt b/samples/client/others/c/bearerAuth/CMakeLists.txt
index 2bfcf58899c0..f7eddc4c612f 100644
--- a/samples/client/others/c/bearerAuth/CMakeLists.txt
+++ b/samples/client/others/c/bearerAuth/CMakeLists.txt
@@ -6,6 +6,7 @@ cmake_policy(SET CMP0063 NEW)
 set(CMAKE_C_VISIBILITY_PRESET default)
 set(CMAKE_VISIBILITY_INLINES_HIDDEN OFF)
 set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS ON)
+set(CMAKE_C_FLAGS "-Werror=implicit-function-declaration")
 
 option(BUILD_SHARED_LIBS "Build using shared libraries" ON)
 
@@ -14,7 +15,7 @@ find_package(OpenSSL)
 if (OPENSSL_FOUND)
     message (STATUS "OPENSSL found")
 
-    set(CMAKE_C_FLAGS "-DOPENSSL")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DOPENSSL")
     if(CMAKE_VERSION VERSION_LESS 3.4)
         include_directories(${OPENSSL_INCLUDE_DIR})
         include_directories(${OPENSSL_INCLUDE_DIRS})
diff --git a/samples/client/petstore/c-useJsonUnformatted/CMakeLists.txt b/samples/client/petstore/c-useJsonUnformatted/CMakeLists.txt
index c97fd637cdb9..68895c666576 100644
--- a/samples/client/petstore/c-useJsonUnformatted/CMakeLists.txt
+++ b/samples/client/petstore/c-useJsonUnformatted/CMakeLists.txt
@@ -6,6 +6,7 @@ cmake_policy(SET CMP0063 NEW)
 set(CMAKE_C_VISIBILITY_PRESET default)
 set(CMAKE_VISIBILITY_INLINES_HIDDEN OFF)
 set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS ON)
+set(CMAKE_C_FLAGS "-Werror=implicit-function-declaration")
 
 option(BUILD_SHARED_LIBS "Build using shared libraries" ON)
 
@@ -14,7 +15,7 @@ find_package(OpenSSL)
 if (OPENSSL_FOUND)
     message (STATUS "OPENSSL found")
 
-    set(CMAKE_C_FLAGS "-DOPENSSL")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DOPENSSL")
     if(CMAKE_VERSION VERSION_LESS 3.4)
         include_directories(${OPENSSL_INCLUDE_DIR})
         include_directories(${OPENSSL_INCLUDE_DIRS})
diff --git a/samples/client/petstore/c-useJsonUnformatted/model/order.c b/samples/client/petstore/c-useJsonUnformatted/model/order.c
index bbbc50e1a316..055dd08a3896 100644
--- a/samples/client/petstore/c-useJsonUnformatted/model/order.c
+++ b/samples/client/petstore/c-useJsonUnformatted/model/order.c
@@ -94,7 +94,7 @@ cJSON *order_convertToJSON(order_t *order) {
 
     // order->status
     if(order->status != openapi_petstore_order_STATUS_NULL) {
-    if(cJSON_AddStringToObject(item, "status", statusorder_ToString(order->status)) == NULL)
+    if(cJSON_AddStringToObject(item, "status", order_status_ToString(order->status)) == NULL)
     {
     goto fail; //Enum
     }
diff --git a/samples/client/petstore/c-useJsonUnformatted/model/pet.c b/samples/client/petstore/c-useJsonUnformatted/model/pet.c
index d95d672eda00..2472e769095d 100644
--- a/samples/client/petstore/c-useJsonUnformatted/model/pet.c
+++ b/samples/client/petstore/c-useJsonUnformatted/model/pet.c
@@ -148,7 +148,7 @@ cJSON *pet_convertToJSON(pet_t *pet) {
 
     // pet->status
     if(pet->status != openapi_petstore_pet_STATUS_NULL) {
-    if(cJSON_AddStringToObject(item, "status", statuspet_ToString(pet->status)) == NULL)
+    if(cJSON_AddStringToObject(item, "status", pet_status_ToString(pet->status)) == NULL)
     {
     goto fail; //Enum
     }
diff --git a/samples/client/petstore/c/model/order.c b/samples/client/petstore/c/model/order.c
index bbbc50e1a316..055dd08a3896 100644
--- a/samples/client/petstore/c/model/order.c
+++ b/samples/client/petstore/c/model/order.c
@@ -94,7 +94,7 @@ cJSON *order_convertToJSON(order_t *order) {
 
     // order->status
     if(order->status != openapi_petstore_order_STATUS_NULL) {
-    if(cJSON_AddStringToObject(item, "status", statusorder_ToString(order->status)) == NULL)
+    if(cJSON_AddStringToObject(item, "status", order_status_ToString(order->status)) == NULL)
     {
     goto fail; //Enum
     }
diff --git a/samples/client/petstore/c/model/pet.c b/samples/client/petstore/c/model/pet.c
index d95d672eda00..2472e769095d 100644
--- a/samples/client/petstore/c/model/pet.c
+++ b/samples/client/petstore/c/model/pet.c
@@ -148,7 +148,7 @@ cJSON *pet_convertToJSON(pet_t *pet) {
 
     // pet->status
     if(pet->status != openapi_petstore_pet_STATUS_NULL) {
-    if(cJSON_AddStringToObject(item, "status", statuspet_ToString(pet->status)) == NULL)
+    if(cJSON_AddStringToObject(item, "status", pet_status_ToString(pet->status)) == NULL)
     {
     goto fail; //Enum
     }