diff --git a/mysqlloadcsv b/mysqlloadcsv
index 3e798ea..6a14fd2 100755
--- a/mysqlloadcsv
+++ b/mysqlloadcsv
@@ -127,7 +127,7 @@ function is_null(value) {
   return value == null_value
 }
 function is_integer(value) {
-  return value ~ /^[0-9]+$/
+  return value ~ /^(0|[1-9][0-9]*)$/
 }
 function is_date_dmy(value) {
   return value ~ /^[0-9][0-9]\/[0-9][0-9]\/[0-9][0-9]$/