diff --git a/Library/Homebrew/cmd/update.rb b/Library/Homebrew/cmd/update.rb
index 4be763b6aa..9890d15ef1 100644
--- a/Library/Homebrew/cmd/update.rb
+++ b/Library/Homebrew/cmd/update.rb
@@ -187,7 +187,13 @@ class Updater
       @stashed = true
     end
 
-    @initial_branch = `git symbolic-ref --short HEAD`.chomp
+
+    begin
+      @initial_branch = `git symbolic-ref --short HEAD 2>/dev/null`.chomp
+    rescue ErrorDuringExecution
+      @initial_branch = ""
+    end
+
     if @initial_branch != "master" && !@initial_branch.empty?
       safe_system "git", "checkout", "master", *quiet
     end
@@ -227,7 +233,7 @@ class Updater
     ignore_interrupts { yield }
   ensure
     if $?.signaled? && $?.termsig == 2 # SIGINT
-      safe_system "git", "checkout", @initial_branch
+      safe_system "git", "checkout", @initial_branch unless @initial_branch.empty?
       safe_system "git", "reset", "--hard", @initial_revision
       safe_system "git", "stash", "pop" if @stashed
     end
diff --git a/Library/Homebrew/test/test_updater.rb b/Library/Homebrew/test/test_updater.rb
index 88f8c23aa7..16f4f2e858 100644
--- a/Library/Homebrew/test/test_updater.rb
+++ b/Library/Homebrew/test/test_updater.rb
@@ -58,7 +58,7 @@ class UpdaterTests < Homebrew::TestCase
     FormulaVersions.stubs(:new).returns(stub(:formula_at_revision => "2.0"))
     @updater.diff = fixture(fixture_name)
     @updater.in_repo_expect("git diff --quiet", true)
-    @updater.in_repo_expect("git symbolic-ref --short HEAD", "master")
+    @updater.in_repo_expect("git symbolic-ref --short HEAD 2>/dev/null", "master")
     @updater.in_repo_expect("git rev-parse -q --verify HEAD", "1234abcd")
     @updater.in_repo_expect("git config core.autocrlf false")
     @updater.in_repo_expect("git pull --ff --no-rebase --quiet origin refs/heads/master:refs/remotes/origin/master")