diff --git a/ext/mysql2_ext.c b/ext/mysql2_ext.c
index 3c95092..ef97a00 100644
--- a/ext/mysql2_ext.c
+++ b/ext/mysql2_ext.c
@@ -146,7 +146,7 @@ static VALUE rb_mysql_client_new(int argc, VALUE * argv, VALUE klass) {
   }
 
   // set default connection timeout behavior
-  if (connect_timeout != 0 && mysql_options(args.mysql, MYSQL_OPT_CONNECT_TIMEOUT, &connect_timeout) != 0) {
+  if (connect_timeout != 0 && mysql_options(args.mysql, MYSQL_OPT_CONNECT_TIMEOUT, (const char *)&connect_timeout) != 0) {
     // TODO: warning - unable to set connection timeout
     rb_warn("%s\n", mysql_error(args.mysql));
   }
@@ -171,7 +171,7 @@ static VALUE rb_mysql_client_new(int argc, VALUE * argv, VALUE klass) {
   return obj;
 }
 
-static VALUE rb_mysql_client_init(int argc, VALUE * argv, VALUE self) {
+static VALUE rb_mysql_client_init(RB_MYSQL_UNUSED int argc, RB_MYSQL_UNUSED VALUE * argv, VALUE self) {
   return self;
 }
 
@@ -205,7 +205,6 @@ static VALUE nogvl_send_query(void *ptr)
 
 static VALUE rb_mysql_client_query(int argc, VALUE * argv, VALUE self) {
   struct nogvl_send_query_args args;
-  MYSQL_RES * result;
   fd_set fdset;
   int fd, retval;
   int async = 0;
@@ -275,7 +274,7 @@ static VALUE rb_mysql_client_escape(VALUE self, VALUE str) {
   }
 }
 
-static VALUE rb_mysql_client_info(VALUE self) {
+static VALUE rb_mysql_client_info(RB_MYSQL_UNUSED VALUE self) {
   VALUE version = rb_hash_new();
   rb_hash_aset(version, sym_id, LONG2FIX(mysql_get_client_version()));
   rb_hash_aset(version, sym_version, rb_str_new2(mysql_get_client_info()));
diff --git a/ext/mysql2_ext.h b/ext/mysql2_ext.h
index f117181..e576a31 100644
--- a/ext/mysql2_ext.h
+++ b/ext/mysql2_ext.h
@@ -17,6 +17,12 @@
 int utf8Encoding, binaryEncoding;
 #endif
 
+#if defined(__GNUC__) && (__GNUC__ >= 3)
+#define RB_MYSQL_UNUSED __attribute__ ((unused))
+#else
+#define RB_MYSQL_UNUSED
+#endif
+
 static VALUE cBigDecimal, cDate, cDateTime;
 ID intern_new, intern_local;
 
@@ -96,7 +102,8 @@ typedef VALUE rb_blocking_function_t(void *);
 static VALUE
 rb_thread_blocking_region(
 	rb_blocking_function_t *func, void *data1,
-	rb_unblock_function_t *ubf, void *data2)
+	RB_MYSQL_UNUSED rb_unblock_function_t *ubf,
+	RB_MYSQL_UNUSED void *data2)
 {
 	VALUE rv;