diff --git a/themes/agnoster.zsh-theme b/themes/agnoster.zsh-theme
index ee0c2afb8..e54346acf 100644
--- a/themes/agnoster.zsh-theme
+++ b/themes/agnoster.zsh-theme
@@ -7,6 +7,9 @@
 #
 # In order for this theme to render correctly, you will need a
 # [Powerline-patched font](https://github.com/Lokaltog/powerline-fonts).
+# Make sure you have a recent version: the code points that Powerline
+# uses changed in 2012, and older versions will display incorrectly,
+# in confusing ways.
 #
 # In addition, I recommend the
 # [Solarized theme](https://github.com/altercation/solarized/) and, if you're
@@ -27,12 +30,21 @@
 
 CURRENT_BG='NONE'
 
-# Fix odd char on mac
-if [[ `uname` == 'Darwin' ]]; then
-    SEGMENT_SEPARATOR='\ue0b0'
-else
-    SEGMENT_SEPARATOR=''
-fi
+# Special Powerline characters
+
+() {
+  local LC_ALL="" LC_CTYPE="en_US.UTF-8"
+  # NOTE: This segment separator character is correct.  In 2012, Powerline changed
+  # the code points they use for their special characters. This is the new code point.
+  # If this is not working for you, you probably have an old version of the 
+  # Powerline-patched fonts installed. Download and install the new version.
+  # Do not submit PRs to change this unless you have reviewed the Powerline code point
+  # history and have new information.
+  # This is defined using a Unicode escape sequence so it is unambiguously readable, regardless of
+  # what font the user is viewing this source code in. Do not replace the
+  # escape sequence with a single literal character.
+  SEGMENT_SEPARATOR=$'\ue0b0' # 
+}
 
 # Begin a segment
 # Takes two arguments, background and foreground. Both can be omitted,
@@ -73,6 +85,12 @@ prompt_context() {
 
 # Git: branch/detached head, dirty status
 prompt_git() {
+
+  local PL_BRANCH_CHAR
+  () {
+    local LC_ALL="" LC_CTYPE="en_US.UTF-8"
+    PL_BRANCH_CHAR=$'\ue0a0'         # 
+  }
   local ref dirty mode repo_path
   repo_path=$(git rev-parse --git-dir 2>/dev/null)
 
@@ -104,7 +122,7 @@ prompt_git() {
     zstyle ':vcs_info:*' formats ' %u%c'
     zstyle ':vcs_info:*' actionformats ' %u%c'
     vcs_info
-    echo -n "${ref/refs\/heads\// }${vcs_info_msg_0_%% }${mode}"
+    echo -n "${ref/refs\/heads\//$PL_BRANCH_CHAR }${vcs_info_msg_0_%% }${mode}"
   fi
 }