diff -rupN HEAD/core/custom_field_api.php PATCH/core/custom_field_api.php
--- HEAD/core/custom_field_api.php	2009-08-02 11:31:38.000000000 -0500
+++ PATCH/core/custom_field_api.php	2009-08-02 11:32:40.000000000 -0500
@@ -1164,7 +1164,7 @@ function custom_field_validate( $p_field
 				$t_valid &= ereg( $t_valid_regexp, $p_value );
 			}
 			// check string length
-			$t_valid &= ( 0 == $t_length_min ) || ( $t_length > $t_length_min );
+			$t_valid &= ( 0 == $t_length_min ) || ( $t_length >= $t_length_min );
 			$t_valid &= ( 0 == $t_length_max ) || ( $t_length <= $t_length_max );
 			break;
 		case CUSTOM_FIELD_TYPE_NUMERIC: