diff --git a/lib/completion.zsh b/lib/completion.zsh
index faea36118..83b6efb66 100644
--- a/lib/completion.zsh
+++ b/lib/completion.zsh
@@ -25,7 +25,7 @@ bindkey -M menuselect '^o' accept-and-infer-next-history
 
 zstyle ':completion:*:*:*:*:*' menu select
 zstyle ':completion:*:*:kill:*:processes' list-colors '=(#b) #([0-9]#) ([0-9a-z-]#)*=01;34=0=01'
-if [ "$PLAT" = "SunOS" ]
+if [ "$OSTYPE[0,7]" = "solaris" ]
 then
   zstyle ':completion:*:*:*:*:processes' command "ps -u `whoami` -o pid,user,comm"
 else
diff --git a/oh-my-zsh.sh b/oh-my-zsh.sh
index 4683c2bc0..c217b91bb 100644
--- a/oh-my-zsh.sh
+++ b/oh-my-zsh.sh
@@ -1,4 +1,3 @@
-PLAT=`uname -s`
 # Check for updates on initial load...
 if [ "$DISABLE_AUTO_UPDATE" != "true" ]; then
   /usr/bin/env ZSH=$ZSH DISABLE_UPDATE_PROMPT=$DISABLE_UPDATE_PROMPT zsh -f $ZSH/tools/check_for_upgrade.sh
diff --git a/plugins/colored-man/colored-man.plugin.zsh b/plugins/colored-man/colored-man.plugin.zsh
index 4956f4346..5c613f49d 100644
--- a/plugins/colored-man/colored-man.plugin.zsh
+++ b/plugins/colored-man/colored-man.plugin.zsh
@@ -1,4 +1,4 @@
-if [ "${PLAT}" = "SunOS" ]
+if [ "$OSTYPE[0,7]" = "solaris" ]
 then
 	if [ ! -x ${HOME}/bin/nroff ]
 	then
diff --git a/tools/check_for_upgrade.sh b/tools/check_for_upgrade.sh
index 1aba9a272..0e8845ab4 100644
--- a/tools/check_for_upgrade.sh
+++ b/tools/check_for_upgrade.sh
@@ -1,13 +1,9 @@
-#!/bin/sh
+#!/usr/bin/env zsh
+
+zmodload zsh/datetime
 
-PLAT=`uname -s`
 function _current_epoch() {
-  if [ "$PLAT" = "SunOS" ]
-  then
-    echo $(($(perl -e 'print time') / 60 / 60 / 24))
-  else
-    echo $(($(date +%s) / 60 / 60 / 24))
-  fi
+  echo $EPOCHSECONDS
 }
 
 function _update_zsh_update() {