diff --git a/pt.lua b/pt.lua
index 6eea391..821634f 100755
--- a/pt.lua
+++ b/pt.lua
@@ -44,10 +44,12 @@ function pt.__call(pt, args)
     self.writer = args.writer or io.write
     self.skeleton = args.skeleton or false
     self.outer = args.alt_order and self.outer_old or self.outer
+    self.noncanon = args.noncanon or false
     self.indent = args.indent or ' '
     self.queued = {}
     self.cache = {}
-    self:inner('__root__', t, '')
+    self.canonicalized = {}
+    self:inner('__root', t, '')
     return self.seen
 end
 
@@ -55,7 +57,12 @@ function pt:write(...)
     self.writer(...)
 end
 
-function pt.safekey(k)
+function pt:safecanon(k)
+    local s = tostring(k)
+    return s:gsub('[^%w_]', '_')
+end
+
+function pt:safekey(k)
     if type(k) == 'table' then
         return 't'..getaddr(k)
     end
@@ -64,7 +71,7 @@ function pt.safekey(k)
     return s:find('[^%w_]') and ('%q'):format(s) or s
 end
 
-function pt.safeval(v, indentation, indent)
+function pt:safeval(v, indentation)
     if type(v) == 'function' then
         return 'f'..getaddr(v)
     end
@@ -74,7 +81,7 @@ function pt.safeval(v, indentation, indent)
     end
     -- TODO: move newline/indentation handling to another function?
     if s:find('[\r\n]') then
-        s = ('\n'..s):gsub('[\r\n]', '\n'..indentation..indent)
+        s = ('\n'..s):gsub('[\r\n]', '\n'..indentation..self.indent)
     end
     --local safe = ('%q'):format(s)
     --return s == safe:sub(2, -2) and s or safe
@@ -85,34 +92,45 @@ end
 function pt:inner(k, v, indentation)
     if type(v) ~= 'table' then
         if self.skeleton then return end
-        self:write(indentation, pt.safekey(k), ': ')
-        self:write(pt.safeval(v, indentation, self.indent), '\n')
+        self:write(indentation, self:safekey(k), ': ')
+        self:write(self:safeval(v, indentation), '\n')
         return
     end
 
     local addr = getaddr(v)
-    self:write(indentation, pt.safekey(k))
+    self:write(indentation, self:safekey(k))
+
+    local canon
+    if not self.noncanon and type(k) ~= 'table' then
+        canon = self.canonicalized[addr]
+        if canon == nil then
+            canon = self:safecanon(k)..'_t'..addr
+            self.canonicalized[addr] = canon
+        end
+    else
+        canon = 't'..addr
+    end
 
     if #indentation > self.depth or self.skipped[addr] then
         --self.skipped[addr] = true -- TODO: extra logics
-        self:write(': #t', addr, '\n')
+        self:write(': #', canon, '\n')
         return
     end
 
     if self.seen[addr] or self.queued[addr] then
-        self:write(': *t', addr, self.seen_elsewhere[addr] and ' #\n' or '\n')
+        self:write(': *', canon, self.seen_elsewhere[addr] and ' #\n' or '\n')
         return
     end
 
     self.seen[addr] = true
 
-    self:write(': &t', addr, '\n')
+    self:write(': &', canon, '\n')
     self:outer(v, indentation..self.indent)
 end
 
 function pt:outer_old(t, indentation)
     if type(t) ~= "table" then
-        local s = pt.safeval(t, indentation, self.indent)
+        local s = self:safeval(t, indentation)
         self:write(indentation, s, '\n')
         return
     end
@@ -151,7 +169,7 @@ end
 
 function pt:outer(t, indentation)
     if type(t) ~= "table" then
-        local s = pt.safeval(t, indentation, self.indent)
+        local s = self:safeval(t, indentation)
         self:write(indentation, s, '\n')
         return
     end