diff --git a/highlighters/main/main-highlighter.zsh b/highlighters/main/main-highlighter.zsh
index 18d5bc4..516600f 100755
--- a/highlighters/main/main-highlighter.zsh
+++ b/highlighters/main/main-highlighter.zsh
@@ -64,6 +64,14 @@ _zsh_highlight_main_highlighter_predicate()
 _zsh_highlight_main_add_region_highlight() {
   integer start=$1 end=$2
   local style=$3
+
+  # The calculation was relative to $PREBUFFER$BUFFER, but region_highlight is
+  # relative to $BUFFER.
+  (( start -= $#PREBUFFER ))
+  (( end -= $#PREBUFFER ))
+
+  (( end < 0 )) && return # bug
+  (( start < 0 )) && start=0 # normal with e.g. multiline strings
   region_highlight+=("$start $end $style")
 }
 
@@ -76,6 +84,7 @@ _zsh_highlight_main_highlighter()
   typeset -a ZSH_HIGHLIGHT_TOKENS_COMMANDSEPARATOR
   typeset -a ZSH_HIGHLIGHT_TOKENS_PRECOMMANDS
   typeset -a ZSH_HIGHLIGHT_TOKENS_FOLLOWED_BY_COMMANDS
+  local buf="$PREBUFFER$BUFFER"
   region_highlight=()
 
   ZSH_HIGHLIGHT_TOKENS_COMMANDSEPARATOR=(
@@ -89,11 +98,11 @@ _zsh_highlight_main_highlighter()
     $ZSH_HIGHLIGHT_TOKENS_COMMANDSEPARATOR $ZSH_HIGHLIGHT_TOKENS_PRECOMMANDS
   )
 
-  for arg in ${(z)BUFFER}; do
+  for arg in ${(z)buf}; do
     local substr_color=0
     local style_override=""
     [[ $start_pos -eq 0 && $arg = 'noglob' ]] && highlight_glob=false
-    ((start_pos+=${#BUFFER[$start_pos+1,-1]}-${#${BUFFER[$start_pos+1,-1]##[[:space:]]#}}))
+    ((start_pos+=${#buf[$start_pos+1,-1]}-${#${buf[$start_pos+1,-1]##[[:space:]]#}}))
     ((end_pos=$start_pos+${#arg}))
     # Parse the sudo command line
     if $sudo; then
diff --git a/highlighters/main/test-data/multiline-string.zsh b/highlighters/main/test-data/multiline-string.zsh
new file mode 100644
index 0000000..f2eb13e
--- /dev/null
+++ b/highlighters/main/test-data/multiline-string.zsh
@@ -0,0 +1,37 @@
+#!/usr/bin/env zsh
+# -------------------------------------------------------------------------------------------------
+# Copyright (c) 2015 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
+# -------------------------------------------------------------------------------------------------
+
+PREBUFFER=$'echo "foo1\n'
+BUFFER='foo2" ./'
+
+expected_region_highlight=(
+  "0 5 $ZSH_HIGHLIGHT_STYLES[double-quoted-argument]" # 'foo2"'
+  "7 8 $ZSH_HIGHLIGHT_STYLES[path]" # './'
+)
diff --git a/tests/test-highlighting.zsh b/tests/test-highlighting.zsh
index 2e72b2b..fdca16f 100755
--- a/tests/test-highlighting.zsh
+++ b/tests/test-highlighting.zsh
@@ -60,13 +60,13 @@ ZSH_HIGHLIGHT_HIGHLIGHTERS=($1)
 for data_file in ${0:h:h}/highlighters/$1/test-data/*; do
 
   # Load the data and prepare checking it.
-  BUFFER= ; expected_region_highlight=(); errors=()
+  PREBUFFER= BUFFER= ; expected_region_highlight=(); errors=()
   echo -n "* ${data_file:t:r}: "
   . $data_file
 
-  # Check the data declares $BUFFER.
-  if [[ ${#BUFFER} -eq 0 ]]; then
-    errors+=("'BUFFER' is not declared or blank.")
+  # Check the data declares $PREBUFFER or $BUFFER.
+  if [[ ${#PREBUFFER} -eq 0 && ${#BUFFER} -eq 0 ]]; then
+    errors+=("Either 'PREBUFFER' or 'BUFFER' must be declared and non-blank")
   else
 
     # Check the data declares $expected_region_highlight.