diff --git a/luamods/wolfadmin/util/bits.lua b/luamods/wolfadmin/util/bits.lua
index 3735faf..6371169 100644
--- a/luamods/wolfadmin/util/bits.lua
+++ b/luamods/wolfadmin/util/bits.lua
@@ -15,9 +15,13 @@
 -- You should have received a copy of the GNU General Public License
 -- along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+local util = require (wolfa_getLuaPath()..".util.util")
+
 local bits = {}
 
 function bits.hasbit(x, b)
+    util.typecheck("bits.hasbit", {x, b}, {"number", "number"})
+
     if b == 0 then
         return x == b
     end
@@ -25,4 +29,4 @@ function bits.hasbit(x, b)
     return x % (b + b) >= b
 end
 
-return bits
\ No newline at end of file
+return bits
diff --git a/luamods/wolfadmin/util/pagination.lua b/luamods/wolfadmin/util/pagination.lua
index 432c7b0..5c04621 100644
--- a/luamods/wolfadmin/util/pagination.lua
+++ b/luamods/wolfadmin/util/pagination.lua
@@ -15,9 +15,13 @@
 -- You should have received a copy of the GNU General Public License
 -- along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+local util = require (wolfa_getLuaPath()..".util.util")
+
 local pagination = {}
 
 function pagination.calculate(count, limit, offset)
+    util.typecheck("pagination.calculate", {count, limit, offset}, {"number", "number", "number"})
+
     limit = limit or 30
     offset = offset or 0
 
diff --git a/luamods/wolfadmin/util/tables.lua b/luamods/wolfadmin/util/tables.lua
index 445e12f..e4fd915 100644
--- a/luamods/wolfadmin/util/tables.lua
+++ b/luamods/wolfadmin/util/tables.lua
@@ -15,9 +15,13 @@
 -- You should have received a copy of the GNU General Public License
 -- along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+local util = require (wolfa_getLuaPath()..".util.util")
+
 local tables = {}
 
 function tables.copy(tbl)
+    util.typecheck("tables.contains", {tbl}, {"table"})
+
     local copy = {}
 
     for key, value in pairs(tbl) do
@@ -28,6 +32,8 @@ function tables.copy(tbl)
 end
 
 function tables.unpack(tbl)
+    util.typecheck("tables.contains", {tbl}, {"table"})
+
     if table.unpack ~= nil then
         return table.unpack(tbl)
     elseif unpack ~= nil then
@@ -36,6 +42,8 @@ function tables.unpack(tbl)
 end
 
 function tables.contains(tbl, needle)
+    util.typecheck("tables.contains", {tbl}, {"table"})
+
     for _, value in pairs(tbl) do
         if value == needle then
             return true
@@ -46,6 +54,8 @@ function tables.contains(tbl, needle)
 end
 
 function tables.find(tbl, needle)
+    util.typecheck("tables.contains", {tbl}, {"table"})
+
     for key, value in pairs(tbl) do
         if value == needle then
             return key
diff --git a/luamods/wolfadmin/util/util.lua b/luamods/wolfadmin/util/util.lua
index 6f6b0ea..a109c2b 100644
--- a/luamods/wolfadmin/util/util.lua
+++ b/luamods/wolfadmin/util/util.lua
@@ -19,6 +19,14 @@ local constants = require (wolfa_getLuaPath()..".util.constants")
 
 local util = {}
 
+function util.typecheck(func, args, types)
+    for idx, arg in ipairs(args) do
+        if type(arg) ~= types[idx] then
+            error("bad argument #"..idx.." to '"..func.."' ("..types[idx].." expected, got "..type(arg)..")", 3)
+        end
+    end
+end
+
 function util.split(str, pat)
     local t = {}    -- NOTE: use {n = 0} in Lua-5.0
     local fpat = "(.-)" .. pat
@@ -41,10 +49,14 @@ function util.split(str, pat)
 end
 
 function util.escape(str)
+    util.typecheck("util.escape", {str}, {"string"})
+
     return string.gsub(str, "([\"'])", "\\%1")
 end
 
 function util.removeColors(str)
+    util.typecheck("util.removeColors", {str}, {"string"})
+
     return string.gsub(str, "(^[%a%d%p])", "")
 end