diff --git a/tabs/search/core.lua b/tabs/search/core.lua
index deefeb6..9cd21b3 100644
--- a/tabs/search/core.lua
+++ b/tabs/search/core.lua
@@ -171,9 +171,12 @@ end
 
 function private.clear_form()
     m.name_input:SetText('')
+    m.name_input:ClearFocus()
     m.exact_checkbox:SetChecked(nil)
     m.min_level_input:SetText('')
+    m.min_level_input:ClearFocus()
     m.max_level_input:SetText('')
+    m.max_level_input:ClearFocus()
     m.usable_checkbox:SetChecked(nil)
     UIDropDownMenu_ClearAll(m.class_dropdown)
     UIDropDownMenu_ClearAll(m.subclass_dropdown)
@@ -841,6 +844,7 @@ function private.export_query_string()
     if components then
         m.search_box:SetText(Aux.filter.query_string({blizzard=components.blizzard, post=m.post_components}))
         m.clear_form()
+        m.filter_input:ClearFocus()
         m.post_components = {}
         m.filter_display:SetText('')
     else
@@ -852,7 +856,7 @@ private.post_components = {}
 
 function private.add_post_filter()
     local name = UIDropDownMenu_GetSelectedValue(m.filter_dropdown)
-    if name and not strfind(Aux.filter.indented_post_query_string(m.post_components), '|n', 20) then
+    if name and getn(Aux.util.filter(m.post_components, function(component) return component[1] == 'operator' end)) < 20 then
         local filter = name
         if Aux.filter.filters[name] and Aux.filter.filters[name].input_type ~= '' then
             filter = filter..'/'..m.filter_input:GetText()
diff --git a/util/filter.lua b/util/filter.lua
index e882907..6153341 100644
--- a/util/filter.lua
+++ b/util/filter.lua
@@ -387,7 +387,7 @@ function public.query(query_string)
     for _, component in components.post do
         if component[1] == 'operator' then
             polish_notation_counter = max(polish_notation_counter, 1)
-            polish_notation_counter = polish_notation_counter + (component[2] or 1) - 1
+            polish_notation_counter = polish_notation_counter + (tonumber(component[2]) or 1) - 1
         elseif component[1] == 'filter' then
             polish_notation_counter = polish_notation_counter - 1
         end
@@ -469,7 +469,7 @@ function private.suggestions(components)
     end
 
     -- subclasses
-    local class_index = Aux.info.item_class_index(blizzard_filters.class or '')
+    local class_index = blizzard_filters.class and Aux.info.item_class_index(blizzard_filters.class)
     if class_index and not blizzard_filters.subclass then
         for _, subclass in ipairs({ GetAuctionItemSubClasses(class_index) }) do
             tinsert(suggestions, subclass)
@@ -477,9 +477,9 @@ function private.suggestions(components)
     end
 
     -- slots
-    local subclass_index = Aux.info.item_subclass_index(class_index, blizzard_filters.subclass or '')
+    local subclass_index = class_index and blizzard_filters.subclass and Aux.info.item_subclass_index(class_index, blizzard_filters.subclass)
     if subclass_index and not blizzard_filters.slot then
-        for _, invtype in ipairs({ GetAuctionInvTypes(class_index, Aux.info.item_subclass_index(Aux.info.item_class_index(blizzard_filters.class), blizzard_filters.subclass)) }) do
+        for _, invtype in ipairs({ GetAuctionInvTypes(class_index, Aux.info.item_subclass_index(class_index, blizzard_filters.subclass)) }) do
             tinsert(suggestions, getglobal(invtype))
         end
     end