diff --git a/Library/Homebrew/cmd/update.sh b/Library/Homebrew/cmd/update.sh
index 6423a028ce..e6ba3d1ee4 100644
--- a/Library/Homebrew/cmd/update.sh
+++ b/Library/Homebrew/cmd/update.sh
@@ -22,22 +22,42 @@ git() {
 git_init_if_necessary() {
   if [[ -n "$HOMEBREW_OSX" ]]
   then
-    OFFICIAL_REMOTE="https://github.com/Homebrew/brew.git"
+    BREW_OFFICIAL_REMOTE="https://github.com/Homebrew/brew"
+    CORE_OFFICIAL_REMOTE="https://github.com/Homebrew/homebrew-core"
   else
-    OFFICIAL_REMOTE="https://github.com/Linuxbrew/brew.git"
+    BREW_OFFICIAL_REMOTE="https://github.com/Linuxbrew/brew"
+    CORE_OFFICIAL_REMOTE="https://github.com/Linuxbrew/homebrew-core"
   fi
 
+  safe_cd "$HOMEBREW_REPOSITORY"
   if [[ ! -d ".git" ]]
   then
     set -e
     trap '{ rm -rf .git; exit 1; }' EXIT
     git init
     git config --bool core.autocrlf false
-    git config remote.origin.url "$OFFICIAL_REMOTE"
+    git config remote.origin.url "$BREW_OFFICIAL_REMOTE"
     git config remote.origin.fetch "+refs/heads/*:refs/remotes/origin/*"
     git fetch --force --depth=1 origin refs/heads/master:refs/remotes/origin/master
     git reset --hard origin/master
-    SKIP_FETCH_HOMEBREW_REPOSITORY=1
+    SKIP_FETCH_BREW_REPOSITORY=1
+    set +e
+    trap - EXIT
+  fi
+
+  [[ -d "$HOMEBREW_LIBRARY/Taps/homebrew/homebrew-core" ]] || return
+  safe_cd "$HOMEBREW_LIBRARY/Taps/homebrew/homebrew-core"
+  if [[ ! -d ".git" ]]
+  then
+    set -e
+    trap '{ rm -rf .git; exit 1; }' EXIT
+    git init
+    git config --bool core.autocrlf false
+    git config remote.origin.url "$CORE_OFFICIAL_REMOTE"
+    git config remote.origin.fetch "+refs/heads/*:refs/remotes/origin/*"
+    git fetch --force --depth=1 origin refs/heads/master:refs/remotes/origin/master
+    git reset --hard origin/master
+    SKIP_FETCH_CORE_REPOSITORY=1
     set +e
     trap - EXIT
   fi
@@ -339,12 +359,13 @@ EOS
   # only allow one instance of brew update
   lock update
 
-  safe_cd "$HOMEBREW_REPOSITORY"
   git_init_if_necessary
   # rename Taps directories
   # this procedure will be removed in the future if it seems unnecessary
   rename_taps_dir_if_necessary
 
+  safe_cd "$HOMEBREW_REPOSITORY"
+
   # kill all of subprocess on interrupt
   trap '{ pkill -P $$; wait; exit 130; }' SIGINT
 
@@ -354,7 +375,8 @@ EOS
   for DIR in "$HOMEBREW_REPOSITORY" "$HOMEBREW_LIBRARY"/Taps/*/*
   do
     [[ -d "$DIR/.git" ]] || continue
-    [[ -n "$SKIP_FETCH_HOMEBREW_REPOSITORY" && "$DIR" = "$HOMEBREW_REPOSITORY" ]] && continue
+    [[ -n "$SKIP_FETCH_BREW_REPOSITORY" && "$DIR" = "$HOMEBREW_REPOSITORY" ]] && continue
+    [[ -n "$SKIP_FETCH_CORE_REPOSITORY" && "$DIR" = "$HOMEBREW_LIBRARY/Taps/homebrew/homebrew-core" ]] && continue
     cd "$DIR" || continue
     UPSTREAM_BRANCH="$(upstream_branch)"
     # the refspec ensures that the default upstream branch gets updated