diff --git a/util/filter.lua b/util/filter.lua
index 3bf5d4a..0665466 100644
--- a/util/filter.lua
+++ b/util/filter.lua
@@ -313,8 +313,7 @@ function M.query(filter_string)
     end
 
     local polish_notation_counter = 0
-    for i = 1, getn(filter.post) do
-	    local component = filter.post[i]
+    for _, component in ipairs(filter.post) do
         if component[1] == 'operator' then
             polish_notation_counter = max(polish_notation_counter, 1)
             polish_notation_counter = polish_notation_counter + (tonumber(component[2]) or 1) - 1
@@ -325,7 +324,7 @@ function M.query(filter_string)
 
     if polish_notation_counter > 0 then
         local suggestions = T
-        for key in filters do
+        for key in pairs(filters) do
             tinsert(suggestions, strlower(key))
         end
         tinsert(suggestions, 'and')
@@ -344,8 +343,7 @@ end
 function M.queries(filter_string)
     local parts = split(filter_string, ';')
     local queries = T
-    for i = 1, getn(parts) do
-        local str = trim(parts[i])
+    for _, str in ipairs(parts) do
         local query, _, error = query(str)
         if not query then
 	        return nil, error
@@ -363,7 +361,7 @@ function suggestions(filter)
 
     tinsert(suggestions, 'and'); tinsert(suggestions, 'or'); tinsert(suggestions, 'not'); tinsert(suggestions, 'tooltip')
 
-    for key in filters do tinsert(suggestions, key) end
+    for key in pairs(filters) do tinsert(suggestions, key) end
 
     -- classes
     if not filter.blizzard.class then
@@ -394,8 +392,8 @@ function suggestions(filter)
 
     -- item names
     if getn(filter.components) == 0 then
-	    for i = 1, getn(aux_auctionable_items) do
-            tinsert(suggestions, aux_auctionable_items[i] .. '/exact')
+	    for _, name in ipairs(aux_auctionable_items) do
+            tinsert(suggestions, name .. '/exact')
         end
     end
 
@@ -404,8 +402,7 @@ end
 
 function M.filter_string(components)
     local query_builder = query_builder()
-    for i = 1, getn(components) do
-	    local component = components[i]
+    for _, component in ipairs(components) do
 	    if component[1] == 'blizzard' then
 		    query_builder.append(component[4] or component[3])
         elseif component[1] == 'operator' then
@@ -494,7 +491,7 @@ function blizzard_query(filter)
         query.slot = slot_index
         query.quality = item_info.quality
     else
-	    for key in temp-S('min_level', 'max_level', 'class', 'subclass', 'slot', 'usable', 'quality') do
+	    for key in pairs(temp-S('min_level', 'max_level', 'class', 'subclass', 'slot', 'usable', 'quality')) do
             query[key] = index(filters[key], 2)
 	    end
     end
@@ -503,7 +500,7 @@ end
 
 function validator(filter)
     local validators = T
-    for i, component in filter.post do
+    for i, component in pairs(filter.post) do
 	    local type, name, param = unpack(component)
         if type == 'filter' then
             validators[i] = filters[name].validator(parse_parameter(filters[name].input_type, param))
diff --git a/util/info.lua b/util/info.lua
index 8772d6e..661ea14 100644
--- a/util/info.lua
+++ b/util/info.lua
@@ -220,7 +220,7 @@ end
 
 function M.tooltip_find(pattern, tooltip)
     local count = 0
-    for _, line in tooltip do
+    for _, line in pairs(tooltip) do
         if line.left_text and strfind(line.left_text, pattern) then
             count = count + 1
         end
@@ -297,7 +297,7 @@ function M.tooltip(setter, arg1, arg2)
 end
 
 function item_charges(tooltip)
-	for _, line in tooltip do
+	for _, line in pairs(tooltip) do
         local pattern = '^' .. gsub(gsub(ITEM_SPELL_CHARGES_P1, '%%d', '(%%d+)'), '%%%d+%$d', '(%%d+)') .. '$'
 
         local _, _, left_charges_string = strfind(line.left_text or '', pattern)
@@ -343,7 +343,7 @@ do
 end
 
 function M.durability(tooltip)
-    for _, line in tooltip do
+    for _, line in pairs(tooltip) do
         local pattern = '^' .. gsub(gsub(DURABILITY_TEMPLATE, '%%d', '(%%d+)'), '%%%d+%$d', '(%%d+)') .. '$'
         local _, _, left_durability_string, left_max_durability_string = strfind(line.left_text or '', pattern)
         local _, _, right_durability_string, right_max_durability_string = strfind(line.right_text or '', pattern)
@@ -386,7 +386,7 @@ function M.item(item_id, suffix_id)
 end
 
 function M.item_class_index(item_class)
-    for i, class in temp-A(GetAuctionItemClasses()) do
+    for i, class in pairs(temp-A(GetAuctionItemClasses())) do
         if strupper(class) == strupper(item_class) then
             return i, class
         end
@@ -394,7 +394,7 @@ function M.item_class_index(item_class)
 end
 
 function M.item_subclass_index(class_index, item_subclass)
-    for i, subclass in temp-A(GetAuctionItemSubClasses(class_index)) do
+    for i, subclass in pairs(temp-A(GetAuctionItemSubClasses(class_index))) do
         if strupper(subclass) == strupper(item_subclass) then
             return i, subclass
         end
@@ -402,7 +402,7 @@ function M.item_subclass_index(class_index, item_subclass)
 end
 
 function M.item_slot_index(class_index, subclass_index, slot_name)
-    for i, slot in temp-A(GetAuctionInvTypes(class_index, subclass_index)) do
+    for i, slot in pairs(temp-A(GetAuctionInvTypes(class_index, subclass_index))) do
         if strupper(_G[slot]) == strupper(slot_name) then
             return i, _G[slot]
         end
diff --git a/util/persistence.lua b/util/persistence.lua
index 728cff9..ef658c5 100644
--- a/util/persistence.lua
+++ b/util/persistence.lua
@@ -67,7 +67,7 @@ end
 function write_tuple(schema, tuple)
     local separator = schema[2]
     local parts = temp-T
-    for i = 3 , getn(schema) do
+    for i = 3, getn(schema) do
         local key, type = next(schema[i])
         tinsert(parts, write(type, tuple[key]))
     end