diff --git a/modules/openapi-generator/src/main/resources/C-libcurl/apiClient.c.mustache b/modules/openapi-generator/src/main/resources/C-libcurl/apiClient.c.mustache
index e5912de027a9..0d1bf5b06593 100644
--- a/modules/openapi-generator/src/main/resources/C-libcurl/apiClient.c.mustache
+++ b/modules/openapi-generator/src/main/resources/C-libcurl/apiClient.c.mustache
@@ -236,7 +236,7 @@ char *assembleHeaderField(char *key, char *value) {
 void postData(CURL *handle, const char *bodyParameters) {
     curl_easy_setopt(handle, CURLOPT_POSTFIELDS, bodyParameters);
     curl_easy_setopt(handle, CURLOPT_POSTFIELDSIZE_LARGE,
-                     strlen(bodyParameters));
+                     (curl_off_t)strlen(bodyParameters));
 }
 
 int lengthOfKeyPair(keyValuePair_t *keyPair) {
diff --git a/samples/client/petstore/c/src/apiClient.c b/samples/client/petstore/c/src/apiClient.c
index 89d6301a98d4..4f8cc3ca0561 100644
--- a/samples/client/petstore/c/src/apiClient.c
+++ b/samples/client/petstore/c/src/apiClient.c
@@ -190,7 +190,7 @@ char *assembleHeaderField(char *key, char *value) {
 void postData(CURL *handle, const char *bodyParameters) {
     curl_easy_setopt(handle, CURLOPT_POSTFIELDS, bodyParameters);
     curl_easy_setopt(handle, CURLOPT_POSTFIELDSIZE_LARGE,
-                     strlen(bodyParameters));
+                     (curl_off_t)strlen(bodyParameters));
 }
 
 int lengthOfKeyPair(keyValuePair_t *keyPair) {