--- pg_createcluster.old	2014-06-12 10:40:45.634894027 +0200
+++ pg_createcluster.new	2014-06-12 10:41:29.859836561 +0200
@@ -234,7 +234,7 @@
     $startconf ne 'manual' && $startconf ne 'disabled';
 
 if ($owneruid) {
-    $owneruid = (getpwnam $owneruid)[2] unless $owneruid =~ /\d+/;
+    $owneruid = (getpwnam $owneruid)[2] unless $owneruid =~ /^\d+$/;
 } elsif ($> == 0) {
     $owneruid = getpwnam 'postgres';
     error 'User postgresql does not exist' unless $owneruid;
@@ -244,7 +244,7 @@
 }
 
 if ($ownergid) {
-    $ownergid = (getgrnam $ownergid)[2] unless $ownergid =~ /\d+/;
+    $ownergid = (getgrnam $ownergid)[2] unless $ownergid =~ /^\d+$/;
 } else {
     $ownergid = (getpwuid $owneruid)[3];
 }