diff --git a/zshrc b/zshrc
index 4d67b26..5d45276 100644
--- a/zshrc
+++ b/zshrc
@@ -49,7 +49,9 @@ if [ -n "$grep" -o -n "$grep_color" ]; then
 	: ${grep:=$(__find_command ggrep grep)}
 	[ -n "$grep_color" -a "$grep_color[1]" != - ] &&
 		grep_color="--color=$grep_color"
-	alias grep="$grep $grep_color"
+	if echo x | $grep $grep_color x &>/dev/null; then
+		alias grep="$grep $grep_color"
+	fi
 fi
 alias fgrep="grep -F"
 
@@ -57,7 +59,9 @@ if [ -n "$ls" -o -n "$ls_color" ]; then
 	: ${ls:=$(__find_command gls ls)}
 	[ -n "$ls_color" -a "$ls_color[1]" != - ] &&
 		ls_color="--color=$ls_color"
-	alias ls="$ls $ls_color"
+	if $ls $ls_color &>/dev/null; then
+		alias ls="$ls $ls_color"
+	fi
 fi
 [ "$ls_on_cd" = yes ] && chpwd() { ls }
 [ "$ls_on_init" = yes ] && ls