diff --git a/app/models/pull_request.rb b/app/models/pull_request.rb
index e0dc93a4d..c40b8cee8 100644
--- a/app/models/pull_request.rb
+++ b/app/models/pull_request.rb
@@ -47,8 +47,7 @@ class PullRequest < Issue
   def merge!(who)
     return false unless can_merge?
     Dir.chdir(path) do
-      system 'git config user.name', '\"#{who.uname}\"'
-      system 'git config user.email', '\"#{who.email}\"'
+      system "git config user.name \"#{who.uname}\" && git config user.email \"#{who.email}\""
       if merge
         merging
         system("git push origin HEAD")
@@ -69,10 +68,7 @@ class PullRequest < Issue
 
   def merge
     clone
-    Dir.chdir(path) do
-      system 'git checkout', data[:base_branch]
-      system 'git merge', '--no-ff', data[:head_branch]
-    end
+    system("cd #{path} && git checkout #{data[:base_branch]} && git merge --no-ff #{data[:head_branch]}")
   end
 
   def clone
@@ -84,8 +80,7 @@ class PullRequest < Issue
     end
     Dir.chdir(path) do
       [data[:base_branch], data[:head_branch]].each do |branch|
-        system 'git checkout', branch
-        system 'git pull origin', branch
+        system "git checkout #{branch} && git pull origin #{branch}"
       end
     end
     # TODO catch errors