diff --git a/lua/grug-far/actions/replace.lua b/lua/grug-far/actions/replace.lua
index 6e9bc341..a7c6914d 100644
--- a/lua/grug-far/actions/replace.lua
+++ b/lua/grug-far/actions/replace.lua
@@ -82,14 +82,14 @@ end
 local function getActionMessage(err, count, total, time)
   local msg = 'replace '
   if err then
-    return msg .. ' failed!'
+    return msg .. 'failed!'
   end
 
   if count == total and total ~= 0 then
-    return msg .. ' completed in ' .. time .. 'ms!'
+    return msg .. 'completed in ' .. time .. 'ms!'
   end
 
-  return msg .. ' ' .. count .. ' / ' .. total .. ' (buffer temporarily not modifiable)'
+  return msg .. count .. ' / ' .. total .. ' (buffer temporarily not modifiable)'
 end
 
 local function replace(params)
@@ -129,13 +129,12 @@ local function replace(params)
     vim.api.nvim_buf_set_option(buf, 'modifiable', true)
 
     state.status = 'error'
-    state.progressCount = nil
     state.actionMessage = getActionMessage(errorMessage)
     resultsList.setError(buf, context, errorMessage)
     renderResultsHeader(buf, context)
   end
 
-  local on_finish_all = vim.schedule_wrap(function(status, errorMessage)
+  local on_finish_all = vim.schedule_wrap(function(status, errorMessage, customActionMessage)
     vim.api.nvim_buf_set_option(buf, 'modifiable', true)
 
     if status == 'error' then
@@ -144,20 +143,27 @@ local function replace(params)
     end
 
     state.status = status
-    state.progressCount = nil
     local time = uv.now() - startTime
     -- not passing in total as 3rd arg cause of paranoia if counts don't end up matching
-    state.actionMessage = status == nil and 'replace cannot work with current arguments!' or
+    state.actionMessage = status == nil and customActionMessage or
       getActionMessage(nil, filesCount, filesCount, time)
     renderResultsHeader(buf, context)
   end)
 
+  if #state.inputs.search == 0 or #state.inputs.replacement == 0 then
+    on_finish_all(nil, nil, 'replace cannot work due to missing search/replacement inputs!')
+    return
+  end
+
   fetchFilesWithMatches({
     inputs = context.state.inputs,
     options = context.options,
     on_fetch_chunk = reportMatchingFilesUpdate,
     on_finish = vim.schedule_wrap(function(status, errorMessage, files)
-      if not status or status == 'error' then
+      if not status then
+        on_finish_all(nil, nil, 'replace cannot work due to improper flags! (blacklisted because of undesirable results)')
+        return
+      elseif status == 'error' then
         on_finish_all(status, errorMessage)
         return
       end
diff --git a/lua/grug-far/actions/search.lua b/lua/grug-far/actions/search.lua
index 78ffb083..7fc449f1 100644
--- a/lua/grug-far/actions/search.lua
+++ b/lua/grug-far/actions/search.lua
@@ -40,7 +40,6 @@ local function search(params)
       state.abortSearch = nil
 
       state.status = status
-      state.progressCount = nil
       if status == 'error' then
         state.stats = nil
         resultsList.setError(buf, context, errorMessage)
diff --git a/lua/grug-far/opts.lua b/lua/grug-far/opts.lua
index 4cbc534c..b61dffc0 100644
--- a/lua/grug-far/opts.lua
+++ b/lua/grug-far/opts.lua
@@ -3,7 +3,7 @@ local M = {}
 local defaultOptions = {
   -- debounce milliseconds for issuing search while user is typing
   -- prevents excesive searching
-  debounceMs = 500,
+  debounceMs = 700,
 
   -- minimum number of chars which will cause a search to happen
   -- prevents performance issues in larger dirs
diff --git a/lua/grug-far/render.lua b/lua/grug-far/render.lua
index 3692fb27..7d6dd456 100644
--- a/lua/grug-far/render.lua
+++ b/lua/grug-far/render.lua
@@ -73,7 +73,8 @@ local function render(params, context)
     extmarkName = "flags",
     icon = 'flagsInput',
     label = "Flags:",
-    placeholder = "ex: --hidden (-.) --ignore-case (-i) --multiline (-U)",
+    -- TODO (sbadragan): make those configurable
+    placeholder = "ex: --hidden (-.) --ignore-case (-i) --multiline (-U) --fixed-strings (-F)",
   }, context))
 
   lineNr = lineNr + BEFORE_RESULTS_LINES
diff --git a/lua/grug-far/render/resultsList.lua b/lua/grug-far/render/resultsList.lua
index 20804655..7fc4cfdd 100644
--- a/lua/grug-far/render/resultsList.lua
+++ b/lua/grug-far/render/resultsList.lua
@@ -1,9 +1,16 @@
 local M = {}
 
+local function setBufLines(buf, start, ending, strict_indexing, replacement)
+  local isModifiable = vim.api.nvim_buf_get_option(buf, 'modifiable')
+  vim.api.nvim_buf_set_option(buf, 'modifiable', true)
+  vim.api.nvim_buf_set_lines(buf, start, ending, strict_indexing, replacement)
+  vim.api.nvim_buf_set_option(buf, 'modifiable', isModifiable)
+end
+
 function M.appendResultsChunk(buf, context, data)
   -- add text
   local lastline = vim.api.nvim_buf_line_count(buf)
-  vim.api.nvim_buf_set_lines(buf, lastline, lastline, false, data.lines)
+  setBufLines(buf, lastline, lastline, false, data.lines)
 
   -- add highlights
   for i = 1, #data.highlights do
@@ -64,7 +71,7 @@ function M.setError(buf, context, error)
   local startLine = context.state.headerRow + 1
 
   local err_lines = vim.split((error and #error > 0) and error or 'Unexpected error!', '\n')
-  vim.api.nvim_buf_set_lines(buf, startLine, startLine, false, err_lines)
+  setBufLines(buf, startLine, startLine, false, err_lines)
 
   for i = startLine, startLine + #err_lines do
     vim.api.nvim_buf_add_highlight(buf, context.namespace, 'DiagnosticError', i, 0, -1)
@@ -74,7 +81,7 @@ end
 function M.clear(buf, context)
   -- remove all lines after heading and add one blank line
   local headerRow = context.state.headerRow
-  vim.api.nvim_buf_set_lines(buf, headerRow, -1, false, { "" })
+  setBufLines(buf, headerRow, -1, false, { "" })
 
   vim.api.nvim_buf_clear_namespace(buf, context.locationsNamespace, 0, -1)
   context.state.resultLocationByExtmarkId = {}
diff --git a/lua/grug-far/rg/blacklistedReplaceFlags.lua b/lua/grug-far/rg/blacklistedReplaceFlags.lua
new file mode 100644
index 00000000..912f3adc
--- /dev/null
+++ b/lua/grug-far/rg/blacklistedReplaceFlags.lua
@@ -0,0 +1,15 @@
+-- TODO (sbadragan): might need to disable some flags, like:
+-- --no-include-zero --no-byte-offset
+-- --hyperlink-format=none
+-- --max-columns=0
+-- --no-max-columns-preview --no-trim
+-- blacklist: --help --quiet
+-- Hmmm, there are just too many things that could completely screw it up ... I think we need a whitelist of useful
+-- flags that we allow the user to pass, otherwise replacing would not work
+return {
+  '--pre',
+  '--pre-glob',
+  '--search-zip', '-z',
+
+  '--help'
+}
diff --git a/lua/grug-far/rg/fetchFilesWithMatches.lua b/lua/grug-far/rg/fetchFilesWithMatches.lua
index 02b4a7a4..e1b144f5 100644
--- a/lua/grug-far/rg/fetchFilesWithMatches.lua
+++ b/lua/grug-far/rg/fetchFilesWithMatches.lua
@@ -1,4 +1,5 @@
 local getArgs = require('grug-far/rg/getArgs')
+local blacklistedReplaceFlags = require('grug-far/rg/blacklistedReplaceFlags')
 local fetchWithRg = require('grug-far/rg/fetchWithRg')
 
 local function fetchFilesWithMatches(params)
@@ -6,7 +7,7 @@ local function fetchFilesWithMatches(params)
 
   local args = getArgs(params.inputs, params.options, {
     '--files-with-matches'
-  })
+  }, blacklistedReplaceFlags)
 
   return fetchWithRg({
     args = args,
diff --git a/lua/grug-far/rg/fetchReplacedFileContent.lua b/lua/grug-far/rg/fetchReplacedFileContent.lua
index 5f4f9bc6..8c498c20 100644
--- a/lua/grug-far/rg/fetchReplacedFileContent.lua
+++ b/lua/grug-far/rg/fetchReplacedFileContent.lua
@@ -1,4 +1,5 @@
 local getArgs = require('grug-far/rg/getArgs')
+local blacklistedReplaceFlags = require('grug-far/rg/blacklistedReplaceFlags')
 local fetchWithRg = require('grug-far/rg/fetchWithRg')
 
 local function fetchReplacedFileContent(params)
@@ -10,7 +11,7 @@ local function fetchReplacedFileContent(params)
     '--no-heading',
     '--no-filename',
     params.file,
-  })
+  }, blacklistedReplaceFlags)
 
   local content = ''
   return fetchWithRg({
diff --git a/lua/grug-far/rg/getArgs.lua b/lua/grug-far/rg/getArgs.lua
index 55488be7..a98f2cfe 100644
--- a/lua/grug-far/rg/getArgs.lua
+++ b/lua/grug-far/rg/getArgs.lua
@@ -1,16 +1,23 @@
--- TODO (sbadragan): might need to disable some flags, like:
--- --no-include-zero --no-byte-offset
--- --hyperlink-format=none
--- --max-columns=0
--- --no-max-columns-preview --no-trim
--- blacklist: --help --quiet
--- Hmmm, there are just too many things that could completely screw it up ... I think we need a whitelist of useful
--- flags that we allow the user to pass, otherwise replacing would not work
-local function isValidArg(arg)
+local function isProperFlag(arg)
   return vim.startswith(arg, '-') and arg ~= '--'
 end
 
-local function getArgs(inputs, options, extraArgs)
+local function isBlacklistedFlag(flag, blacklistedFlags)
+  if not blacklistedFlags then
+    return false
+  end
+
+  for i = 1, #blacklistedFlags do
+    local badFlag = blacklistedFlags[i]
+    if flag == badFlag or vim.startswith(flag, badFlag .. ' ') or vim.startswith(flag, badFlag .. '=') then
+      return true
+    end
+  end
+
+  return false
+end
+
+local function getArgs(inputs, options, extraArgs, blacklistedFlags)
   local args = nil
   if #inputs.search < (options.minSearchChars or 1) then
     return nil
@@ -26,7 +33,10 @@ local function getArgs(inputs, options, extraArgs)
   local extraUserArgs = options.extraRgArgs and vim.trim(options.extraRgArgs) or ''
   if #extraUserArgs > 0 then
     for arg in string.gmatch(extraUserArgs, "%S+") do
-      if isValidArg(arg) then
+      if isBlacklistedFlag(arg, blacklistedFlags) then
+        return nil
+      end
+      if isProperFlag(arg) then
         table.insert(args, arg)
       end
     end
@@ -34,7 +44,10 @@ local function getArgs(inputs, options, extraArgs)
 
   if #inputs.flags > 0 then
     for flag in string.gmatch(inputs.flags, "%S+") do
-      if isValidArg(flag) then
+      if isBlacklistedFlag(flag, blacklistedFlags) then
+        return nil
+      end
+      if isProperFlag(flag) then
         table.insert(args, flag)
       end
     end