diff --git a/atm-core.lua b/atm-core.lua
index 6623b7e..f68eba6 100644
--- a/atm-core.lua
+++ b/atm-core.lua
@@ -80,9 +80,9 @@ function formspecs.pay(name, fields, guessed_amount)
 
             if exc < 0 then
                 lurkcoin.get_exchange_rate(fields.amount, fields.server or
-                        lurkcoin.server_name, function(data)
+                        lurkcoin.server_name, function(data, msg)
                     if not data then
-                        fields._err = 'That server does not exist!'
+                        fields._err = msg
                     end
                     fields._exchange_rate = data
                     return lurkcoin.show_atm(name, 'pay', fields)
@@ -239,14 +239,18 @@ function lurkcoin.show_atm(name, page, params)
         page, params))
 end
 
-minetest.register_on_player_receive_fields(function(player, formname, fields)
+minetest.register_on_player_receive_fields(function(player, formname, raw)
     if formname ~= 'lurkcoin:atm' then return end
 
     local name = player:get_player_name()
 
-    -- These probably don't need to be deleted.
-    fields._err = nil
-    fields._exchange_rate = nil
+    -- Do a shallow copy in case some other mod relies on "fields" not changing.
+    local fields = {}
+    for k, v in pairs(raw) do
+        if type(k) == 'string' and k:sub(1, 1) ~= '_' then
+            fields[k] = v
+        end
+    end
 
     if withdrawls then
         if fields.deposit then
@@ -333,11 +337,11 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
                 lurkcoin.show_atm(name, 'pay', fields)
                 return
             elseif fields.server then
-                fields.server = fields.server:gsub('^ *(.-) *$', '%1')
+                fields.server = fields.server:trim()
             end
 
             if fields.user then
-                fields.user = fields.user:gsub('^ *(.-) *$', '%1')
+                fields.user = fields.user:trim()
             end
 
             if not fields.server or fields.server == '' then
@@ -359,7 +363,6 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
                 return
             end
         end
-        fields._err = nil
         lurkcoin.show_atm(name, 'pay', fields)
     elseif fields.home then
         lurkcoin.show_atm(name, 'main')
diff --git a/core.lua b/core.lua
index 7cabb6c..37b09e4 100644
--- a/core.lua
+++ b/core.lua
@@ -36,18 +36,21 @@ lurkcoin.user_agent = 'Minetest ' .. minetest.get_version().string ..
 
 -- Download functions
 local function get(url, data, callback)
+    -- To prevent race conditions, these callbacks wait until at least the next
+    --  globalstep.
     if not data then
         data = {}
     elseif not http then
-        return callback({
+        minetest.after(0, callback, {
             completed = true,
             succeeded = false,
             timeout   = true,
             code      = 500,
             data      = 'ERROR: The lurkcoin mod is not in secure.http_mods!'
         })
+        return
     elseif not lurkcoin.server_name or not token then
-        return callback({
+        minetest.after(0, callback, {
             completed = true,
             succeeded = false,
             timeout   = true,
@@ -55,6 +58,7 @@ local function get(url, data, callback)
             data      = 'ERROR: The lurkcoin mod does not have (correct) ' ..
                 'account credentials!'
         })
+        return
     end
 
     data.name  = lurkcoin.server_name
@@ -146,9 +150,15 @@ function lurkcoin.get_exchange_rate(amount, to, callback)
     }, function(res)
         if res.code == 200 then
             local amount = tonumber(res.data)
-            if amount == amount then return callback(amount) end
+            if amount == amount then return callback(amount, nil) end
         end
-        return callback(nil)
+        local msg
+        if res.code == 502 then
+            msg = 'That server does not exist!'
+        else
+            msg = res.data
+        end
+        return callback(nil, tostring(msg))
     end)
 end