diff --git a/hiredis.c b/hiredis.c
index 13da532..fdbbd6d 100644
--- a/hiredis.c
+++ b/hiredis.c
@@ -839,7 +839,7 @@ void *redisCommand(redisContext *c, const char *format, ...) {
  * Always returns NULL. In a non-blocking context this will never fail because
  * this function does not do any I/O. In a blocking context this function will
  * have no effect (a callback in a blocking context makes no sense). */
-void *redisCommandWithCallback(redisContext *c, redisCallbackFn *fn, const void *privdata, const char *format, ...) {
+void *redisCommandWithCallback(redisContext *c, redisCallbackFn *fn, void *privdata, const char *format, ...) {
     va_list ap;
     sds cmd;
     int status;
diff --git a/hiredis.h b/hiredis.h
index 8a0e2aa..b8c69bb 100644
--- a/hiredis.h
+++ b/hiredis.h
@@ -80,7 +80,7 @@ struct redisContext; /* need forward declaration of redisContext */
 typedef void (redisContextCallbackFn)(struct redisContext*, void*);
 
 /* Reply callback prototype and container */
-typedef void (redisCallbackFn)(struct redisContext*, redisReply*, const void*);
+typedef void (redisCallbackFn)(struct redisContext*, redisReply*, void*);
 
 /* Callback containers */
 typedef struct redisContextCallback {
@@ -90,7 +90,7 @@ typedef struct redisContextCallback {
 
 typedef struct redisCallback {
     redisCallbackFn *fn;
-    const void *privdata;
+    void *privdata;
 } redisCallback;
 
 /* Context for a connection to Redis */
@@ -163,6 +163,6 @@ void *redisCommand(redisContext *c, const char *format, ...);
  *
  * Note: when called with a blocking context, this function will not do
  * anything and immediately returns NULL. */
-void *redisCommandWithCallback(redisContext *c, redisCallbackFn *fn, const void *privdata, const char *format, ...);
+void *redisCommandWithCallback(redisContext *c, redisCallbackFn *fn, void *privdata, const char *format, ...);
 
 #endif
diff --git a/test.c b/test.c
index cbf8149..4c55118 100644
--- a/test.c
+++ b/test.c
@@ -203,7 +203,7 @@ static void __test_callback(redisContext *c, void *privdata) {
 }
 
 static long __test_reply_callback_flags = 0;
-static void __test_reply_callback(redisContext *c, redisReply *reply, const void *privdata) {
+static void __test_reply_callback(redisContext *c, redisReply *reply, void *privdata) {
     ((void)c);
     /* Shift to detect execution order */
     __test_reply_callback_flags <<= 8;