diff --git a/mx_mysql.c b/mx_mysql.c
index ac066671..aff7bc02 100644
--- a/mx_mysql.c
+++ b/mx_mysql.c
@@ -699,11 +699,9 @@ static int _mx_mysql_bind_string(struct mx_mysql_bind *b, unsigned int index, ch
 
 static int _mx_mysql_bind_validate(struct mx_mysql_bind *b)
 {
-    int i;
-
     mx_assert_return_minus_errno(b, EINVAL);
 
-    for (i=0; i < b->count; i++) {
+    for (unsigned long i=0; i < b->count; i++) {
         if (!(b->data[i].flags)) {
             return -(errno=EBADSLT);
         }
@@ -1015,7 +1013,6 @@ int mx_mysql_statement_fetch(struct mx_mysql_stmt *stmt)
 {
     struct mx_mysql_bind *r;
     int res;
-    int col;
     char *str;
     int no_error = 1;
 
@@ -1044,7 +1041,7 @@ int mx_mysql_statement_fetch(struct mx_mysql_stmt *stmt)
     }
 
     r = &stmt->result;
-    for (col = 0; col < r->count; col++) {
+    for (unsigned long col = 0; col < r->count; col++) {
         if (r->bind[col].buffer_type == MYSQL_TYPE_STRING) {
             str = mx_calloc_forever(r->data[col].length + 1, sizeof(*str));
 
@@ -1063,7 +1060,7 @@ int mx_mysql_statement_fetch(struct mx_mysql_stmt *stmt)
         if (!(r->data[col].is_error))
             continue;
 
-        mx_log_debug("WARNING: result data returned in column with index %d was truncated. query was:", col);
+        mx_log_debug("WARNING: result data returned in column with index %lu was truncated. query was:", col);
         mx_log_debug("       \\ %s", stmt->statement);
         no_error = 0;
     }
@@ -1165,7 +1162,6 @@ static int _mx_mysql_do_statement(struct mx_mysql *mysql, char *query, struct mx
     struct mx_mysql_stmt *stmt = NULL;
     unsigned long long num_rows = 0;
     int res;
-    int cnt = 0;
     char *tmpdata;
 
     assert(mysql);
@@ -1196,7 +1192,7 @@ static int _mx_mysql_do_statement(struct mx_mysql *mysql, char *query, struct mx
     if (result && result->count && num_rows) {
         tmpdata = mx_calloc_forever(num_rows, size);
 
-        for (cnt = 0; cnt < num_rows; cnt++) {
+        for (unsigned long cnt = 0; cnt < num_rows; cnt++) {
             res = mx_mysql_statement_fetch(stmt);
             if (res < 0) {
                 mx_log_err("mx_mysql_statement_fetch(): %m");