diff --git a/README.md b/README.md
index 11fdf88..14adf80 100644
--- a/README.md
+++ b/README.md
@@ -20,6 +20,7 @@ snippet from [percol](https://github.com/mooz/percol).
 - [peco](https://github.com/peco/peco)
 - [psh](http://www.zsh.org/)
 - `tac`, or `tail` with support for `-r` option.
+- `perl`, `awk`, or `uniq` for if de-duplication is turned on.
 
 ## Installation
 
@@ -76,7 +77,35 @@ snippet from [percol](https://github.com/mooz/percol).
 
 3. Start a new terminal session.
 
-### Recommended Peco Config
+## Configuration Options
+
+### `ZSH_PECO_HISTORY_DEDUP`
+
+De-duplicates all history entries before they are handed over to peco. Disabled
+by default.
+
+To enable, set the `ZSH_PECO_HISTORY_DEDUP` environment variable to a non-zero
+value before zsh-peco-history is loaded.
+
+This is useful if you often have a lot of duplicate entries when searching
+through your history. However in that case it often enough to configure ZSH to
+not save duplicate commands to history in the first place. This can be done by
+setting the following options:
+
+```
+setopt HIST_EXPIRE_DUPS_FIRST
+setopt HIST_IGNORE_DUPS
+setopt HIST_IGNORE_ALL_DUPS
+setopt HIST_FIND_NO_DUPS
+setopt HIST_SAVE_NO_DUPS
+```
+
+[Oh My Zsh](https://github.com/robbyrussell/oh-my-zsh) for example sets the
+above options, and more in it's
+[`history.zsh`](https://github.com/mattjj/my-oh-my-zsh/blob/b1d4bab329456e9a4af49237064d9a3b6566f1b0/history.zsh)
+file.
+
+## Recommended Peco Config
 
 You don't have to use this config, it's simply what I personally use. So here's
 what my `~/.peco/config.json` file looks like:
diff --git a/zsh-peco-history.zsh b/zsh-peco-history.zsh
index fa30923..332dada 100644
--- a/zsh-peco-history.zsh
+++ b/zsh-peco-history.zsh
@@ -6,29 +6,35 @@
 # Requirements:
 #  - peco: https://github.com/peco/peco
 #  - tac, or tail with support for -r option
+#  - perl, awk, or uniq for if de-duplication is turned on
 #
 # Based on: https://github.com/mooz/percol#zsh-history-search
 
 if which peco &> /dev/null; then
   function peco_select_history() {
-    local tac
-    local uniq
+    local parse_cmd
+
     if (( $+commands[gtac] )); then
-      tac="gtac"
+      parse_cmd="gtac"
     elif (( $+commands[tac] )); then
-      tac="tac"
+      parse_cmd="tac"
     else
-      tac="tail -r"
+      parse_cmd="tail -r"
     fi
-    if (( $+commands[perl] )); then
-      uniq="perl -ne 'print unless \$seen{\$_}++'"
-    elif (( $+commands[awk] )); then
-      uniq="awk '!seen[\$0]++'"
-    else
-      uniq="uniq"
+
+    if [ -n "$ZSH_PECO_HISTORY_DEDUP" ]; then
+      if (( $+commands[perl] )); then
+        parse_cmd="$parse_cmd | perl -ne 'print unless \$seen{\$_}++'"
+      elif (( $+commands[awk] )); then
+        parse_cmd="$parse_cmd | awk '!seen[\$0]++'"
+      else
+        parse_cmd="$parse_cmd | uniq"
+      fi
     fi
-    BUFFER=$(fc -l -n 1 | eval $tac | eval $uniq | \
+
+    BUFFER=$(fc -l -n 1 | eval $parse_cmd | \
                peco --layout=bottom-up --query "$LBUFFER")
+
     CURSOR=$#BUFFER # move cursor
     zle -R -c       # refresh
   }