diff --git a/highlighters/main/main-highlighter.zsh b/highlighters/main/main-highlighter.zsh
index 544550b..c08a6d9 100644
--- a/highlighters/main/main-highlighter.zsh
+++ b/highlighters/main/main-highlighter.zsh
@@ -756,6 +756,10 @@ _zsh_highlight_main_highlighter_highlight_string()
             elif [[ ${arg:$i} =~ ^[{]([A-Za-z_][A-Za-z0-9_]*|[0-9]+)[}] ]] ; then
               (( k += $#MATCH )) # highlight the parameter name and braces
               (( i += $#MATCH )) # skip past it
+            elif [[ $arg[i+1] == '$' ]]; then
+              # $$ - pid
+              (( k += 1 )) # highlight both dollar signs
+              (( i += 1 )) # don't consider the second one as introducing another parameter expansion
             elif [[ $arg[i+1] == $'\x28' ]]; then
               # Highlight just the '$'.
             else
diff --git a/highlighters/main/test-data/dollar-dollar.zsh b/highlighters/main/test-data/dollar-dollar.zsh
new file mode 100644
index 0000000..79d7f7d
--- /dev/null
+++ b/highlighters/main/test-data/dollar-dollar.zsh
@@ -0,0 +1,39 @@
+#!/usr/bin/env zsh
+# -------------------------------------------------------------------------------------------------
+# Copyright (c) 2016 zsh-syntax-highlighting contributors
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without modification, are permitted
+# provided that the following conditions are met:
+#
+#  * Redistributions of source code must retain the above copyright notice, this list of conditions
+#    and the following disclaimer.
+#  * Redistributions in binary form must reproduce the above copyright notice, this list of
+#    conditions and the following disclaimer in the documentation and/or other materials provided
+#    with the distribution.
+#  * Neither the name of the zsh-syntax-highlighting contributors nor the names of its contributors
+#    may be used to endorse or promote products derived from this software without specific prior
+#    written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+# FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
+# IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+# -------------------------------------------------------------------------------------------------
+# -*- mode: zsh; sh-indentation: 2; indent-tabs-mode: nil; sh-basic-offset: 2; -*-
+# vim: ft=zsh sw=2 ts=2 et
+# -------------------------------------------------------------------------------------------------
+
+BUFFER=': "$$ $$foo"'
+
+expected_region_highlight=(
+  '1 1 builtin' # :
+  '3 3 double-quoted-argument' # "
+  '4 5 dollar-double-quoted-argument' # $$
+  '7 8 dollar-double-quoted-argument' # $$
+  '9 12 double-quoted-argument' # foo"
+)