diff --git a/README.md b/README.md
index 567271c..5e3a1f0 100644
--- a/README.md
+++ b/README.md
@@ -259,6 +259,14 @@ export FZF_COMPLETION_TRIGGER='~~'
 
 # Options to fzf command
 export FZF_COMPLETION_OPTS='+c -x'
+
+# Use ag instead of the default find command for listing candidates.
+# - The first argument to the function is the base path to start traversal
+# - Note that ag only lists files not directories
+# - See the source code (completion.{bash,zsh}) for the details.
+_fzf_compgen_paths() {
+  ag -g "" "$1"
+}
 ```
 
 #### Supported commands
diff --git a/shell/completion.bash b/shell/completion.bash
index ef3a965..9d84ce5 100644
--- a/shell/completion.bash
+++ b/shell/completion.bash
@@ -10,6 +10,26 @@
 # - $FZF_COMPLETION_TRIGGER (default: '**')
 # - $FZF_COMPLETION_OPTS    (default: empty)
 
+# To use custom commands instead of find, override _fzf_compgen_{path,dir}
+if ! declare -f _fzf_compgen_path > /dev/null; then
+  _fzf_compgen_path() {
+    echo "$1"
+    \find -L "$1" \
+      -name .git -prune -o -name .svn -prune -o \( -type d -o -type f -o -type l \) \
+      -a -not -path "$1" -print 2> /dev/null | sed 's@^\./@@'
+  }
+fi
+
+if ! declare -f _fzf_compgen_dir > /dev/null; then
+  _fzf_compgen_dir() {
+    \find -L "$1" \
+      -name .git -prune -o -name .svn -prune -o -type d \
+      -a -not -path "$1" -print 2> /dev/null | sed 's@^\./@@'
+  }
+fi
+
+###########################################################
+
 _fzf_orig_completion_filter() {
   sed 's/^\(.*-F\) *\([^ ]*\).* \([^ ]*\)$/export _fzf_orig_completion_\3="\1 %s \3 #\2";/' |
   awk -F= '{gsub(/[^a-z0-9_= ;]/, "_", $1); print $1"="$2}'
@@ -113,7 +133,7 @@ __fzf_generic_path_completion() {
         [ -z "$dir" ] && dir='.'
         [ "$dir" != "/" ] && dir="${dir/%\//}"
         tput sc
-        matches=$(\find -L "$dir" $1 -a -not -path "$dir" -print 2> /dev/null | sed 's@^\./@@' | $fzf $FZF_COMPLETION_OPTS $2 -q "$leftover" | while read item; do
+        matches=$(eval "$1 $(printf %q "$dir")" | $fzf $FZF_COMPLETION_OPTS $2 -q "$leftover" | while read item; do
           printf "%q$3 " "$item"
         done)
         matches=${matches% }
@@ -171,21 +191,16 @@ _fzf_complete() {
 }
 
 _fzf_path_completion() {
-  __fzf_generic_path_completion \
-    "-name .git -prune -o -name .svn -prune -o ( -type d -o -type f -o -type l )" \
-    "-m" "" "$@"
+  __fzf_generic_path_completion _fzf_compgen_path "-m" "" "$@"
 }
 
+# Deprecated. No file only completion.
 _fzf_file_completion() {
-  __fzf_generic_path_completion \
-    "-name .git -prune -o -name .svn -prune -o ( -type f -o -type l )" \
-    "-m" "" "$@"
+  _fzf_path_completion "$@"
 }
 
 _fzf_dir_completion() {
-  __fzf_generic_path_completion \
-    "-name .git -prune -o -name .svn -prune -o -type d" \
-    "" "/" "$@"
+  __fzf_generic_path_completion _fzf_compgen_dir "" "/" "$@"
 }
 
 _fzf_complete_kill() {
@@ -239,13 +254,12 @@ _fzf_complete_unalias() {
 # fzf options
 complete -o default -F _fzf_opts_completion fzf
 
-d_cmds="cd pushd rmdir"
-f_cmds="
+d_cmds="${FZF_COMPLETION_DIR_COMMANDS:-cd pushd rmdir}"
+a_cmds="
   awk cat diff diff3
   emacs emacsclient ex file ftp g++ gcc gvim head hg java
   javac ld less more mvim nvim patch perl python ruby
-  sed sftp sort source tail tee uniq vi view vim wc xdg-open"
-a_cmds="
+  sed sftp sort source tail tee uniq vi view vim wc xdg-open
   basename bunzip2 bzip2 chmod chown curl cp dirname du
   find git grep gunzip gzip hg jar
   ln ls mv open rm rsync scp
@@ -256,7 +270,7 @@ x_cmds="kill ssh telnet unset unalias export"
 if [ "$_fzf_completion_loaded" != '0.10.8' ]; then
   # Really wish I could use associative array but OSX comes with bash 3.2 :(
   eval $(complete | \grep '\-F' | \grep -v _fzf_ |
-    \grep -E " ($(echo $d_cmds $f_cmds $a_cmds $x_cmds | sed 's/ /|/g' | sed 's/+/\\+/g'))$" | _fzf_orig_completion_filter)
+    \grep -E " ($(echo $d_cmds $a_cmds $x_cmds | sed 's/ /|/g' | sed 's/+/\\+/g'))$" | _fzf_orig_completion_filter)
   export _fzf_completion_loaded=0.10.8
 fi
 
@@ -278,21 +292,16 @@ _fzf_defc() {
   fi
 }
 
-# Directory
-for cmd in $d_cmds; do
-  _fzf_defc "$cmd" _fzf_dir_completion "-o nospace -o plusdirs"
-done
-
-# File
-for cmd in $f_cmds; do
-  _fzf_defc "$cmd" _fzf_file_completion "-o default -o bashdefault"
-done
-
 # Anything
 for cmd in $a_cmds; do
   _fzf_defc "$cmd" _fzf_path_completion "-o default -o bashdefault"
 done
 
+# Directory
+for cmd in $d_cmds; do
+  _fzf_defc "$cmd" _fzf_dir_completion "-o nospace -o plusdirs"
+done
+
 unset _fzf_defc
 
 # Kill completion
@@ -307,4 +316,4 @@ complete -F _fzf_complete_unset -o default -o bashdefault unset
 complete -F _fzf_complete_export -o default -o bashdefault export
 complete -F _fzf_complete_unalias -o default -o bashdefault unalias
 
-unset cmd d_cmds f_cmds a_cmds x_cmds
+unset cmd d_cmds a_cmds x_cmds
diff --git a/shell/completion.zsh b/shell/completion.zsh
index 6e2d932..c7dee7a 100644
--- a/shell/completion.zsh
+++ b/shell/completion.zsh
@@ -10,12 +10,32 @@
 # - $FZF_COMPLETION_TRIGGER (default: '**')
 # - $FZF_COMPLETION_OPTS    (default: empty)
 
+# To use custom commands instead of find, override _fzf_compgen_{path,dir}
+if ! declare -f _fzf_compgen_path > /dev/null; then
+  _fzf_compgen_path() {
+    echo "$1"
+    \find -L "$1" \
+      -name .git -prune -o -name .svn -prune -o \( -type d -o -type f -o -type l \) \
+      -a -not -path "$1" -print 2> /dev/null | sed 's@^\./@@'
+  }
+fi
+
+if ! declare -f _fzf_compgen_dir > /dev/null; then
+  _fzf_compgen_dir() {
+    \find -L "$1" \
+      -name .git -prune -o -name .svn -prune -o -type d \
+      -a -not -path "$1" -print 2> /dev/null | sed 's@^\./@@'
+  }
+fi
+
+###########################################################
+
 __fzf_generic_path_completion() {
-  local base lbuf find_opts fzf_opts suffix tail fzf dir leftover matches nnm
+  local base lbuf compgen fzf_opts suffix tail fzf dir leftover matches nnm
   # (Q) flag removes a quoting level: "foo\ bar" => "foo bar"
   base=${(Q)1}
   lbuf=$2
-  find_opts=$3
+  compgen=$3
   fzf_opts=$4
   suffix=$5
   tail=$6
@@ -33,7 +53,7 @@ __fzf_generic_path_completion() {
       [ -z "$dir" ] && dir='.'
       [ "$dir" != "/" ] && dir="${dir/%\//}"
       dir=${~dir}
-      matches=$(\find -L "$dir" ${=find_opts} -a -not -path "$dir" -print 2> /dev/null | sed 's@^\./@@' | ${=fzf} ${=FZF_COMPLETION_OPTS} ${=fzf_opts} -q "$leftover" | while read item; do
+      matches=$(eval "$compgen $(printf %q "$dir")" | ${=fzf} ${=FZF_COMPLETION_OPTS} ${=fzf_opts} -q "$leftover" | while read item; do
         printf "%q$suffix " "$item"
       done)
       matches=${matches% }
@@ -50,14 +70,12 @@ __fzf_generic_path_completion() {
 }
 
 _fzf_path_completion() {
-  __fzf_generic_path_completion "$1" "$2" \
-    "-name .git -prune -o -name .svn -prune -o ( -type d -o -type f -o -type l )" \
+  __fzf_generic_path_completion "$1" "$2" _fzf_compgen_path \
     "-m" "" " "
 }
 
 _fzf_dir_completion() {
-  __fzf_generic_path_completion "$1" "$2" \
-    "-name .git -prune -o -name .svn -prune -o -type d" \
+  __fzf_generic_path_completion "$1" "$2" _fzf_compgen_dir \
     "" "/" ""
 }
 
@@ -145,7 +163,7 @@ fzf-completion() {
     zle redisplay
   # Trigger sequence given
   elif [ ${#tokens} -gt 1 -a "$tail" = "$trigger" ]; then
-    d_cmds=(cd pushd rmdir)
+    d_cmds=(${=FZF_COMPLETION_DIR_COMMANDS:-cd pushd rmdir})
 
     [ -z "$trigger"      ] && prefix=${tokens[-1]} || prefix=${tokens[-1]:0:-${#trigger}}
     [ -z "${tokens[-1]}" ] && lbuf=$LBUFFER        || lbuf=${LBUFFER:0:-${#tokens[-1]}}
diff --git a/test/test_go.rb b/test/test_go.rb
index efbbf25..a8f75c6 100644
--- a/test/test_go.rb
+++ b/test/test_go.rb
@@ -1269,7 +1269,7 @@ module CompletionTest
     tmux.send_keys 'C-u'
     tmux.send_keys 'cat /tmp/fzf\ test/**', :Tab, pane: 0
     tmux.until(1) { |lines| lines.item_count > 0 }
-    tmux.send_keys :Enter
+    tmux.send_keys 'C-K', :Enter
     tmux.until do |lines|
       tmux.send_keys 'C-L'
       lines[-1].end_with?('/tmp/fzf\ test/foobar')
@@ -1339,6 +1339,20 @@ module CompletionTest
       tmux.send_keys 'C-L'
       lines[-1] == "kill #{pid}"
     end
+
+    def test_custom_completion
+      tmux.send_keys '_fzf_compgen_path() { echo "\$1"; seq 10; }', :Enter
+      tmux.prepare
+      tmux.send_keys 'ls /tmp/**', :Tab, pane: 0
+      tmux.until(1) { |lines| lines.item_count == 11 }
+      tmux.send_keys :BTab, :BTab, :BTab
+      tmux.until(1) { |lines| lines[-2].include? '(3)' }
+      tmux.send_keys :Enter
+      tmux.until do |lines|
+        tmux.send_keys 'C-L'
+        lines[-1] == "ls /tmp 1 2"
+      end
+    end
   ensure
     Process.kill 'KILL', pid.to_i rescue nil if pid
   end