diff --git a/Library/Homebrew/cmd/update.sh b/Library/Homebrew/cmd/update.sh
index c87c16a118..ee6048ca8c 100644
--- a/Library/Homebrew/cmd/update.sh
+++ b/Library/Homebrew/cmd/update.sh
@@ -349,12 +349,13 @@ EOS
   fi
 
   # check permissions
-  if [[ "$HOMEBREW_PREFIX" = "/usr/local" && ! -w /usr/local ]]
+  if [[ -e "$HOMEBREW_CELLAR" && ! -w "$HOMEBREW_CELLAR" ]]
   then
     odie <<EOS
-/usr/local is not writable. You should change the ownership
-and permissions of /usr/local back to your user account:
-  sudo chown -R \$(whoami) /usr/local
+$HOMEBREW_CELLAR is not writable. You should change the
+ownership and permissions of $HOMEBREW_CELLAR back to your
+user account:
+  sudo chown -R \$(whoami) $HOMEBREW_CELLAR
 EOS
   fi
 
diff --git a/Library/Homebrew/diagnostic.rb b/Library/Homebrew/diagnostic.rb
index 230c96bfc8..c064e9169a 100644
--- a/Library/Homebrew/diagnostic.rb
+++ b/Library/Homebrew/diagnostic.rb
@@ -324,21 +324,37 @@ module Homebrew
         EOS
       end
 
-      def check_access_usr_local
-        return unless HOMEBREW_PREFIX.to_s == "/usr/local"
-        return if HOMEBREW_PREFIX.writable_real?
+      def check_access_homebrew_cellar
+        return if HOMEBREW_CELLAR.writable_real?
 
         <<-EOS.undent
-          /usr/local is not writable.
-          Even if this directory was writable when you installed Homebrew, other
-          software may change permissions on this directory. For example, upgrading
-          to OS X El Capitan has been known to do this. Some versions of the
-          "InstantOn" component of Airfoil or running Cocktail cleanup/optimizations
-          are known to do this as well.
+          #{HOMEBREW_CELLAR} is not writable.
 
-          You should change the ownership and permissions of /usr/local back to
-          your user account.
-            sudo chown -R $(whoami) /usr/local
+          You should change the ownership and permissions of #{HOMEBREW_CELLAR}
+          back to your user account.
+            sudo chown -R $(whoami) #{HOMEBREW_CELLAR}
+        EOS
+      end
+
+      def check_access_top_level_directories
+        not_writable_dirs = []
+
+        (Keg::TOP_LEVEL_DIRECTORIES + ["opt"]).each do |dir|
+          path = HOMEBREW_PREFIX/dir
+          next unless path.exist?
+          next if path.writable_real?
+          not_writable_dirs << path
+        end
+
+        return if not_writable_dirs.empty?
+
+        <<-EOS.undent
+          The following directories are not writable:
+          #{not_writable_dirs.join("\n")}
+
+          You should change the ownership and permissions of these directories.
+          back to your user account.
+            sudo chown -R $(whoami) #{not_writable_dirs.join(" ")}
         EOS
       end
 
diff --git a/share/doc/homebrew/Troubleshooting.md b/share/doc/homebrew/Troubleshooting.md
index b02c196763..31682a7bf9 100644
--- a/share/doc/homebrew/Troubleshooting.md
+++ b/share/doc/homebrew/Troubleshooting.md
@@ -13,7 +13,7 @@ brew gist-logs <formula>
 * Read through the [Common Issues](Common-Issues.md).
 * If you’re installing something Java-related, maybe you need to install Java (`brew cask install java`)?
 * Check that **Command Line Tools for Xcode (CLT)** and/or **Xcode** are up to date.
-* If things fail with permissions errors, check the permissions in `/usr/local`. If you’re unsure what to do, you can `sudo chown -R $(whoami) /usr/local`.
+* If things fail with permissions errors, check the permissions of `/usr/local`'s subdirectories. If you’re unsure what to do, you can `cd /usr/local && sudo chown -R $(whoami) bin etc include lib sbin share var Frameworks`.
 
 ## Check to see if the issue has been reported
 * Check the [issue tracker](https://github.com/Homebrew/homebrew-core/issues) to see if someone else has already reported the same issue.