diff --git a/fw-addr-lists.rsc b/fw-addr-lists.rsc
index fece692c..c85cc8bf 100644
--- a/fw-addr-lists.rsc
+++ b/fw-addr-lists.rsc
@@ -117,7 +117,7 @@
           :local Branch;
           :if ($Address ~ "^[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}(/[0-9]{1,2})?\$") do={
             :local Net $Address;
-            :local CIDR "32";
+            :local CIDR 32;
             :local Slash [ :find $Address "/" ];
             :if ([ :typeof $Slash ] = "num") do={
               :set Net [ :toip [ :pick $Address 0 $Slash ] ]
@@ -130,7 +130,7 @@
           }
           :if ($Address ~ "^[0-9a-zA-Z]*:[0-9a-zA-Z:\\.]+(/[0-9]{1,3})?\$") do={
             :local Net $Address;
-            :local CIDR "128";
+            :local CIDR 128;
             :local Slash [ :find $Address "/" ];
             :if ([ :typeof $Slash ] = "num") do={
               :set Net [ :toip6 [ :pick $Address 0 $Slash ] ]
diff --git a/global-functions.rsc b/global-functions.rsc
index 7b3a56fd..b7cff0fe 100644
--- a/global-functions.rsc
+++ b/global-functions.rsc
@@ -1004,27 +1004,27 @@
   :local FuncName $0;
   :local CIDR [ :tostr $1 ];
 
+  :global IfThenElse;
+  :global MAX;
+  :global MIN;
+
   :global NetMask6Cache;
 
-  :global GetRandom20CharAlNum;
-
-  :if ([ :typeof $NetMask6Cache ] = "array") do={
+  :if ([ :typeof ($NetMask6Cache->$CIDR) ] = "ip6") do={
     :return ($NetMask6Cache->$CIDR);
   }
 
-  :set NetMask6Cache { "128"=(~::) };
-
-  :local GenList ($FuncName . "-" . [ $GetRandom20CharAlNum ]);
-  :for I from=0 to=127 do={
-    /ipv6/firewall/address-list/add dynamic=yes timeout=1m list=$GenList address=((~::) . "/" . $I) comment=$I;
-  }
-  :foreach FwAddrList in=[ /ipv6/firewall/address-list/find where list=$GenList ] do={
-    :local Address [ /ipv6/firewall/address-list/get $FwAddrList ];
-    :set ($NetMask6Cache->($Address->"comment")) \
-      [ :toip6 [ :pick ($Address->"address") 0 [ :find ($Address->"address") "/" ] ] ];
+  :if ([ :typeof $NetMask6Cache ] = "nothing") do={
+    :set NetMask6Cache ({});
   }
 
-  :return ($NetMask6Cache->$CIDR);
+  :local Mask "";
+  :for I from=0 to=7 do={
+    :set Mask ($Mask . [ :convert from=num to=hex (0xffff - (0xffff >> [ :tonum [ $MIN [ $MAX ($CIDR - ((16 * $I))) 0 ] 16 ] ])) ] . [ $IfThenElse ($I < 7) ":" ]);
+  }
+  :set Mask [ :toip6 $Mask ];
+  :set ($NetMask6Cache->$CIDR) $Mask;
+  :return $Mask;
 }
 
 # prepare NotificationFunctions array
diff --git a/mod/ipcalc.rsc b/mod/ipcalc.rsc
index fecf6f26..d65d4724 100644
--- a/mod/ipcalc.rsc
+++ b/mod/ipcalc.rsc
@@ -36,21 +36,32 @@
   :local Input [ :tostr $1 ];
 
   :global NetMask4;
+  :global NetMask6;
 
-  :local Address [ :toip [ :pick $Input 0 [ :find $Input "/" ] ] ];
+  :local Address [ :pick $Input 0 [ :find $Input "/" ] ];
   :local Bits [ :tonum [ :pick $Input ([ :find $Input "/" ] + 1) [ :len $Input ] ] ];
-  :local Mask [ $NetMask4 $Bits ];
+  :local Mask;
+  :local One;
+  :if ([ :typeof [ :toip $Address ] ] = "ip") do={
+    :set Address [ :toip $Address ];
+    :set Mask [ $NetMask4 $Bits ];
+    :set One 0.0.0.1;
+  } else={
+    :set Address [ :toip6 $Address ];
+    :set Mask [ $NetMask6 $Bits ];
+    :set One ::1;
+  }
 
-  :local Return {
+  :local Return ({
     "address"=$Address;
     "netmask"=$Mask;
     "networkaddress"=($Address & $Mask);
     "networkbits"=$Bits;
     "network"=(($Address & $Mask) . "/" . $Bits);
-    "hostmin"=(($Address & $Mask) | 0.0.0.1);
-    "hostmax"=(($Address | ~$Mask) ^ 0.0.0.1);
+    "hostmin"=(($Address & $Mask) | $One);
+    "hostmax"=(($Address | ~$Mask) ^ $One);
     "broadcast"=($Address | ~$Mask);
-  }
+  });
 
   :return $Return;
 }