diff --git a/README.md b/README.md
index a01edf1..ca52db0 100644
--- a/README.md
+++ b/README.md
@@ -5,14 +5,14 @@ Better host completion for ssh in Zsh.
 [![asciicast](https://asciinema.org/a/381405.svg)](https://asciinema.org/a/381405)
 
 - [zsh-ssh](#zsh-ssh)
-    - [Installation](#installation)
-        - [Zinit](#zinit)
-        - [Antigen](#antigen)
-        - [Oh My Zsh](#oh-my-zsh)
-        - [Sheldon](#sheldon)
-        - [Manual (Git Clone)](#manual-git-clone)
-    - [Usage](#usage)
-        - [SSH Config Example](#ssh-config-example)
+  - [Installation](#installation)
+    - [Zinit](#zinit)
+    - [Antigen](#antigen)
+    - [Oh My Zsh](#oh-my-zsh)
+    - [Sheldon](#sheldon)
+    - [Manual (Git Clone)](#manual-git-clone)
+  - [Usage](#usage)
+    - [SSH Config Example](#ssh-config-example)
 
 ## Installation
 
@@ -34,15 +34,15 @@ antigen bundle sunlei/zsh-ssh
 
 1. Clone this repository into `$ZSH_CUSTOM/plugins` (by default `~/.oh-my-zsh/custom/plugins`)
 
-    ```shell
-    git clone https://github.com/sunlei/zsh-ssh ${ZSH_CUSTOM:-~/.oh-my-zsh/custom}/plugins/zsh-ssh
-    ```
+   ```shell
+   git clone https://github.com/sunlei/zsh-ssh ${ZSH_CUSTOM:-~/.oh-my-zsh/custom}/plugins/zsh-ssh
+   ```
 
 2. Add the plugin to the list of plugins for Oh My Zsh to load (inside `~/.zshrc`):
 
-    ```shell
-    plugins=(zsh-ssh $plugins)
-    ```
+   ```shell
+   plugins=(zsh-ssh $plugins)
+   ```
 
 3. Start a new terminal session.
 
@@ -50,10 +50,10 @@ antigen bundle sunlei/zsh-ssh
 
 1. Add this config to `~/.config/sheldon/plugins.toml`
 
-    ```toml
-    [plugins.zsh-ssh]
-    github = 'sunlei/zsh-ssh'
-    ```
+   ```toml
+   [plugins.zsh-ssh]
+   github = 'sunlei/zsh-ssh'
+   ```
 
 2. Run `sheldon lock` to install the plugin.
 
@@ -63,15 +63,15 @@ antigen bundle sunlei/zsh-ssh
 
 1. Clone this repository somewhere on your machine. For example: `~/.zsh/zsh-ssh`.
 
-    ```shell
-    git clone https://github.com/sunlei/zsh-ssh ~/.zsh/zsh-ssh
-    ```
+   ```shell
+   git clone https://github.com/sunlei/zsh-ssh ~/.zsh/zsh-ssh
+   ```
 
 2. Add the following to your `.zshrc`:
 
-    ```shell
-    source ~/.zsh/zsh-ssh/zsh-ssh.zsh
-    ```
+   ```shell
+   source ~/.zsh/zsh-ssh/zsh-ssh.zsh
+   ```
 
 3. Start a new terminal session.
 
@@ -95,3 +95,17 @@ Host Development-Host
     IdentityFile ~/.ssh/development-host
     #_Desc For Development
 ```
+
+Include files are also supported. For example, your main config can include separate files:
+
+~/.ssh/config
+
+```text
+Include ~/.ssh/config.d/company.ssh_config
+Include ~/.ssh/config.d/home.ssh_config
+Include ~/.ssh/config.d/work.ssh_config
+
+# OR
+
+Include ~/.ssh/config.d/*.ssh_config
+```
diff --git a/zsh-ssh.zsh b/zsh-ssh.zsh
index c402950..134d408 100644
--- a/zsh-ssh.zsh
+++ b/zsh-ssh.zsh
@@ -9,6 +9,8 @@ setopt no_beep # don't beep
 zstyle ':completion:*:ssh:*' hosts off # disable built-in hosts completion
 
 SSH_CONFIG_FILE="${SSH_CONFIG_FILE:-$HOME/.ssh/config}"
+typeset -gi _zsh_ssh_parse_depth=0
+typeset -gA _zsh_ssh_seen_config_files
 
 # Parse the file and handle the include directive.
 _parse_config_file() {
@@ -16,56 +18,83 @@ _parse_config_file() {
   setopt localoptions rematchpcre
   unsetopt nomatch
 
+  local input_path="$1"
+  local config_file_path
+  local line raw_path expanded include_file_path
+  local -a include_paths
+
   # Resolve the full path of the input config file
-  local config_file_path=$(realpath "$1")
-
-  # Read the file line by line
-  while IFS= read -r line || [[ -n "$line" ]]; do
-    # Match lines starting with 'Include'
-    if [[ $line =~ ^[Ii]nclude[[:space:]=]+(.*) ]] && (( $#match > 0 )); then
-      # Split the rest of the line into individual paths
-      local include_paths=(${(z)match[1]})
-
-      for raw_path in "${include_paths[@]}"; do
-        # Expand ~ and environment variables in the path
-        eval "local expanded=\${(e)raw_path}"
-        # local expanded="${raw_path/#~/$HOME}"
-
-        # If path is relative, resolve it relative to the current config file
-        if [[ "$expanded" != /* ]]; then
-          if [[ "$expanded" == ~* ]]; then
+  config_file_path=$(realpath "$input_path" 2>/dev/null) || return 0
+
+  # If previous parse was interrupted, reset stale global state.
+  if (( _zsh_ssh_parse_depth <= 0 )); then
+    _zsh_ssh_parse_depth=0
+    unset _zsh_ssh_seen_config_files
+    typeset -gA _zsh_ssh_seen_config_files
+  fi
+
+  (( _zsh_ssh_parse_depth++ ))
+  {
+    if [[ -n "${_zsh_ssh_seen_config_files[$config_file_path]}" ]]; then
+      return 0
+    fi
+    _zsh_ssh_seen_config_files[$config_file_path]=1
+
+    # Read the file line by line
+    while IFS= read -r line || [[ -n "$line" ]]; do
+      # Match lines starting with 'Include'
+      if [[ $line =~ ^[[:space:]]*[Ii][Nn][Cc][Ll][Uu][Dd][Ee][[:space:]=]+(.*) ]] && (( $#match > 0 )); then
+        # Split the rest of the line into individual paths
+        include_paths=(${(z)match[1]})
+
+        for raw_path in "${include_paths[@]}"; do
+          # Expand ~ and environment variables in the path
+          expanded="${(e)raw_path}"
+
+          # Expand a literal leading ~ before testing whether the path is relative.
+          if [[ $expanded == '~'* ]]; then
             expanded="${expanded/#\~/$HOME}"
-          else
-            expanded="$(dirname "$config_file_path")/$expanded"
           fi
-        fi
 
-        # Expand wildcards (e.g. *.conf) and loop over each matched file
-        for include_file_path in $~expanded; do
-          if [[ -f "$include_file_path" ]]; then
-            # Separate includes with a blank line (for readability)
-            echo ""
-            # Recursively parse included files
-            _parse_config_file "$include_file_path"
+          # If path is relative, resolve it relative to the current config file
+          if [[ "$expanded" != /* ]]; then
+            expanded="$(dirname "$config_file_path")/$expanded"
           fi
+
+          # Expand wildcards (e.g. *.conf) and loop over each matched file
+          for include_file_path in ${~expanded}(N); do
+            if [[ -f "$include_file_path" ]]; then
+              # Separate includes with a blank line (for readability)
+              echo ""
+              # Recursively parse included files
+              _parse_config_file "$include_file_path"
+            fi
+          done
         done
-      done
-    else
-      # Print normal (non-Include) lines
-      echo "$line"
+      else
+        # Print normal (non-Include) lines
+        echo "$line"
+      fi
+    done < "$config_file_path"
+  } always {
+    (( _zsh_ssh_parse_depth-- ))
+    if (( _zsh_ssh_parse_depth <= 0 )); then
+      _zsh_ssh_parse_depth=0
+      unset _zsh_ssh_seen_config_files
+      typeset -gA _zsh_ssh_seen_config_files
     fi
-  done < "$config_file_path"
+  }
 }
 
 _ssh_host_list() {
   local ssh_config host_list
 
-  ssh_config=$(_parse_config_file $SSH_CONFIG_FILE)
-  ssh_config=$(echo $ssh_config | command grep -v -E "^\s*#[^_]")
+  ssh_config=$(_parse_config_file "$SSH_CONFIG_FILE")
+  ssh_config=$(printf "%s\n" "$ssh_config" | command grep -v -E "^\s*#[^_]")
   # Ensure blank line before each Host/Match block for AWK paragraph mode (RS="")
-  ssh_config=$(echo $ssh_config | command awk '/^[[:space:]]*[Hh]ost[[:space:]]|^[[:space:]]*[Mm]atch[[:space:]]/{print ""} {print}')
+  ssh_config=$(printf "%s\n" "$ssh_config" | command awk '/^[[:space:]]*[Hh]ost[[:space:]]|^[[:space:]]*[Mm]atch[[:space:]]/{print ""} {print}')
 
-  host_list=$(echo $ssh_config | command awk '
+  host_list=$(printf "%s\n" "$ssh_config" | command awk '
     function join(array, start, end, sep, result, i) {
       # https://www.gnu.org/software/gawk/manual/html_node/Join-Function.html
       if (sep == "")
@@ -183,7 +212,7 @@ _ssh_host_list() {
   fi
   host_list=$(printf "%s\n" "$host_list" | command sort -u)
 
-  echo $host_list
+  printf "%s\n" "$host_list"
 }
 
 
@@ -201,9 +230,9 @@ Alias|->|Hostname|User|Desc
 ─────|──|────────|────|────
 "
 
-  host_list="${header}\n${host_list}"
+  host_list="${header}"$'\n'"${host_list}"
 
-  echo $host_list | command column -t -s '|'
+  printf "%s\n" "$host_list" | command column -t -s '|'
 }
 
 _set_lbuffer() {