diff --git a/docs/libcurl/opts/CURLOPT_WRITEFUNCTION.md b/docs/libcurl/opts/CURLOPT_WRITEFUNCTION.md
index 61a02c4c5e..dbf4cb35e2 100644
--- a/docs/libcurl/opts/CURLOPT_WRITEFUNCTION.md
+++ b/docs/libcurl/opts/CURLOPT_WRITEFUNCTION.md
@@ -85,7 +85,7 @@ struct memory {
   size_t size;
 };
 
-static size_t cb(void *data, size_t size, size_t nmemb, void *clientp)
+static size_t cb(char *data, size_t size, size_t nmemb, void *clientp)
 {
   size_t realsize = size * nmemb;
   struct memory *mem = (struct memory *)clientp;