diff --git a/async.c b/async.c
index 83d88ec..9d7cad1 100644
--- a/async.c
+++ b/async.c
@@ -62,7 +62,8 @@ void __redisAppendCommand(redisContext *c, char *cmd, size_t len);
 
 /* Functions managing dictionary of callbacks for pub/sub. */
 static unsigned int callbackHash(const void *key) {
-    return dictGenHashFunction((unsigned char*)key,sdslen((char*)key));
+    return dictGenHashFunction((const unsigned char*)key
+                               , sdslen((const char*)key));
 }
 
 static void *callbackValDup(void *privdata, const void *src) {
@@ -73,7 +74,7 @@ static void *callbackValDup(void *privdata, const void *src) {
 }
 
 static int callbackKeyCompare(void *privdata, const void *key1, const void *key2) {
-    int l1, l2;
+    const int l1, l2;
     ((void) privdata);
 
     l1 = sdslen((sds)key1);
diff --git a/hiredis.c b/hiredis.c
index 80599db..65f84d0 100644
--- a/hiredis.c
+++ b/hiredis.c
@@ -665,7 +665,7 @@ int redisReaderGetReply(redisReader *r, void **reply) {
 }
 
 /* Calculate the number of bytes needed to represent an integer as string. */
-static int intlen(int i) {
+static const int intlen(int i) {
     int len = 0;
     if (i < 0) {
         len++;
@@ -679,7 +679,7 @@ static int intlen(int i) {
 }
 
 /* Helper that calculates the bulk length given a certain string length. */
-static size_t bulklen(size_t len) {
+static const size_t bulklen(size_t len) {
     return 1+intlen(len)+2+len+2;
 }