diff --git a/plugins/bundler/bundler.plugin.zsh b/plugins/bundler/bundler.plugin.zsh
index 2e657e5a8..e390f8620 100644
--- a/plugins/bundler/bundler.plugin.zsh
+++ b/plugins/bundler/bundler.plugin.zsh
@@ -4,18 +4,6 @@ alias bp="bundle package"
 alias bo="bundle open"
 alias bu="bundle update"
 
-bundler_version=`bundle version | cut -d' ' -f3`
-if [[ $bundler_version > '1.4.0' || $bundler_version = '1.4.0' ]]; then
-  if [[ "$(uname)" == 'Darwin' ]]
-  then
-    local cores_num="$(sysctl hw.ncpu | awk '{print $2}')"
-  else
-    local cores_num="$(nproc)"
-  fi
-  eval "alias bi='bundle install --jobs=$cores_num'"
-else
-  alias bi='bundle install' 
-fi
 
 # The following is based on https://github.com/gma/bundler-exec
 
@@ -44,14 +32,28 @@ _run-with-bundler() {
   fi
 }
 
-## Main program
-for cmd in $bundled_commands; do
-  eval "function unbundled_$cmd () { $cmd \$@ }"
-  eval "function bundled_$cmd () { _run-with-bundler $cmd \$@}"
-  alias $cmd=bundled_$cmd
+if _bundler-installed; then
+	bundler_version=`bundle version | cut -d' ' -f3`
+	if [[ $bundler_version > '1.4.0' || $bundler_version = '1.4.0' ]]; then
+		if [[ "$(uname)" == 'Darwin' ]]
+		then
+			local cores_num="$(sysctl hw.ncpu | awk '{print $2}')"
+		else
+			local cores_num="$(nproc)"
+		fi
+		eval "alias bi='bundle install --jobs=$cores_num'"
+	else
+		alias bi='bundle install' 
+	fi
 
-  if which _$cmd > /dev/null 2>&1; then
-        compdef _$cmd bundled_$cmd=$cmd
-  fi
-done
+	## Main program
+	for cmd in $bundled_commands; do
+		eval "function unbundled_$cmd () { $cmd \$@ }"
+		eval "function bundled_$cmd () { _run-with-bundler $cmd \$@}"
+		alias $cmd=bundled_$cmd
 
+		if which _$cmd > /dev/null 2>&1; then
+			compdef _$cmd bundled_$cmd=$cmd
+		fi
+	done
+fi
diff --git a/plugins/jira/jira.plugin.zsh b/plugins/jira/jira.plugin.zsh
index 9aa192c1e..739ee7142 100644
--- a/plugins/jira/jira.plugin.zsh
+++ b/plugins/jira/jira.plugin.zsh
@@ -31,7 +31,7 @@ open_jira_issue () {
 
   if [ -z "$1" ]; then
     echo "Opening new issue"
-    `open $jira_url/secure/CreateIssue!default.jspa`
+    $open_cmd "$jira_url/secure/CreateIssue!default.jspa"
   else
     echo "Opening issue #$1"
     if [[ "x$JIRA_RAPID_BOARD" = "xtrue" ]]; then
diff --git a/themes/agnoster.zsh-theme b/themes/agnoster.zsh-theme
index 2db565266..762f63c5b 100644
--- a/themes/agnoster.zsh-theme
+++ b/themes/agnoster.zsh-theme
@@ -124,7 +124,7 @@ prompt_hg() {
 			else
 				prompt_segment green black
 			fi
-			echo -n " $rev@$branch" $st
+			echo -n "☿ $rev@$branch" $st
 		fi
 	fi
 }
@@ -137,7 +137,7 @@ prompt_dir() {
 # Virtualenv: current working virtualenv
 prompt_virtualenv() {
   local virtualenv_path="$VIRTUAL_ENV"
-  if [[ -n $virtualenv_path && -z $VIRTUAL_ENV_DISABLE_PROMPT ]]; then
+  if [[ -n $virtualenv_path && -n $VIRTUAL_ENV_DISABLE_PROMPT ]]; then
     prompt_segment blue black "(`basename $virtualenv_path`)"
   fi
 }
diff --git a/themes/linuxonly b/themes/linuxonly.zsh-theme
similarity index 100%
rename from themes/linuxonly
rename to themes/linuxonly.zsh-theme