diff --git a/screen/screenrc.symlink b/screen/screenrc.symlink
index befd11d5..c3a7d9aa 100644
--- a/screen/screenrc.symlink
+++ b/screen/screenrc.symlink
@@ -14,3 +14,6 @@ termcapinfo xterm* ti@:te@
 
 # Support updating the title bar from the screened shell.
 termcapinfo xterm* 'hs:ts=\E]0;:fs=\007:ds=\E]0;\007'
+
+# Use the SSH agent socket that is created by oh-my-zsh/plugins/ssh-agent.
+setenv SSH_AUTH_SOCK /tmp/ssh-agent-$USER-screen
diff --git a/ssh/postinit.zsh b/ssh/postinit.zsh
index 87c3e8bb..75ed66ab 100644
--- a/ssh/postinit.zsh
+++ b/ssh/postinit.zsh
@@ -15,9 +15,13 @@ if [[ -n "$SSH_AGENT_PID" ]] && [[ -n "$SSH_AUTH_SOCK" ]]; then
   setx SSH_AUTH_SOCK "$auth_sock" > /dev/null
   unset auth_sock
 else
-  verbose Removing system-wide export $fg[yellow]\$SSH_AGENT_PID$reset_color
-  setx SSH_AGENT_PID "" > /dev/null
+  if [[ -n "$SSH_AGENT_PID" ]]; then
+    verbose Removing system-wide export $fg[yellow]\$SSH_AGENT_PID$reset_color
+    setx SSH_AGENT_PID "" > /dev/null
+  fi
 
-  verbose Removing system-wide export $fg[yellow]\$SSH_AUTH_SOCK$reset_color
-  setx SSH_AUTH_SOCK "" > /dev/null
+  if [[ -n "$SSH_AGENT_SOCK" ]]; then
+    verbose Removing system-wide export $fg[yellow]\$SSH_AUTH_SOCK$reset_color
+    setx SSH_AUTH_SOCK "" > /dev/null
+  fi
 fi
diff --git a/ssh/zprofile.zsh b/ssh/zprofile.zsh
index c1cb27b8..3a8274f8 100644
--- a/ssh/zprofile.zsh
+++ b/ssh/zprofile.zsh
@@ -1,4 +1,9 @@
 if [[ -n "$SSH_CONNECTION" ]] && (($+commands[screen])); then
+  if [[ -n  "$SSH_AUTH_SOCK" ]]; then
+    verbose Symlinking $fg[yellow]$SSH_AUTH_SOCK$reset_color to $fg[yellow]/tmp/ssh-agent-$USER-screen$reset_color
+    ln -sf "$SSH_AUTH_SOCK" "/tmp/ssh-agent-$USER-screen"
+  fi
+
   verbose Starting $fg[green]screen$reset_color because we\'re connected using $fg[green]ssh$reset_color
   /usr/bin/screen -dRq ssh && exit
 fi
diff --git a/tmux/tmux.conf.symlink b/tmux/tmux.conf.symlink
index 0c8ba919..6b37853b 100644
--- a/tmux/tmux.conf.symlink
+++ b/tmux/tmux.conf.symlink
@@ -32,3 +32,6 @@ set -s escape-time 0
 
 set -g mouse on
 bind -n WheelUpPane if-shell -F -t = "#{mouse_any_flag}" "send-keys -M" "if -Ft= '#{pane_in_mode}' 'send-keys -M' 'copy-mode -e; send-keys -M'"
+
+# Always copy SSH environment variables.
+set -g update-environment "SSH_CLIENT SSH_CONNECTION SSH_TTY SSH_AUTH_SOCK SSH_ASKPASS"