--- a/config/autoconf.mk.in
+++ b/config/autoconf.mk.in
@@ -148,16 +148,18 @@ MOZ_MORK = @MOZ_MORK@
 MOZ_MORKREADER = @MOZ_MORKREADER@
 MOZ_NO_FAST_LOAD = @MOZ_NO_FAST_LOAD@
 NS_PRINTING = @NS_PRINTING@
 MOZ_CRASHREPORTER = @MOZ_CRASHREPORTER@
 MOZ_HELP_VIEWER = @MOZ_HELP_VIEWER@
 
 TAR=@TAR@
 
+MAKENSISU=@MAKENSISU@
+
 RM = rm -f
 
 # The MOZ_UI_LOCALE var is used to build a particular locale. Do *not*
 # use the var to change any binary files. Do *not* use this var unless you
 # write rules for the "clean-locale" and "locale" targets.
 MOZ_UI_LOCALE = @MOZ_UI_LOCALE@
 
 MOZ_COMPONENTS_VERSION_SCRIPT_LDFLAGS = @MOZ_COMPONENTS_VERSION_SCRIPT_LDFLAGS@

--- a/configure.in
+++ b/configure.in
@@ -5433,22 +5433,42 @@ case "$target_os" in
         ;;
 esac
 
 MOZ_ARG_DISABLE_BOOL(installer,
 [  --disable-installer     Disable building of installer],
     MOZ_INSTALLER=,
     MOZ_INSTALLER=1 )
 if test -n "$MOZ_INSTALLER" -a "$OS_ARCH" = "WINNT"; then
-    # Disable installer for Windows builds that use the new toolkit if NSIS
-    # isn't in the path.
-    MOZ_PATH_PROGS(MAKENSIS, makensis)
-    if test -z "$MAKENSIS" || test "$MAKENSIS" = ":"; then
-        AC_MSG_ERROR([To build the installer makensis is required in your path. To build without the installer reconfigure using --disable-installer.])
+    # Disable installer for Windows builds that use the new toolkit if the
+    # required major version and minimum minor version of Unicode NSIS isn't in
+    # the path.
+    REQ_NSIS_MAJOR_VER=2
+    MIN_NSIS_MINOR_VER=33
+    MOZ_PATH_PROGS(MAKENSISU, $MAKENSISU makensisu-2.46 makensisu makensis)
+    if test -z "$MAKENSISU" || test "$MAKENSISU" = ":"; then
+        AC_MSG_ERROR([To build the installer you must have the latest MozillaBuild or Unicode NSIS with a major version of $REQ_NSIS_MAJOR_VER and a minimum minor version of $MIN_NSIS_MINOR_VER in your path. To build without the installer reconfigure using --disable-installer.])
     fi
+    changequote(,)
+    MAKENSISU_VER=`"$MAKENSISU" -version 2>/dev/null | sed -e '/-Unicode/!s/.*//g' -e 's/^v\([0-9]\+\.[0-9]\+\)\-Unicode$/\1/g'`
+    changequote([,])
+    if test ! "$MAKENSISU_VER" == ""; then
+        MAKENSISU_MAJOR_VER=`echo $MAKENSISU_VER | $AWK -F\. '{ print $1 }'`
+        MAKENSISU_MINOR_VER=`echo $MAKENSISU_VER | $AWK -F\. '{ print $2 }'`
+    fi
+    AC_MSG_CHECKING([for Unicode NSIS with major version == $REQ_NSIS_MAJOR_VER and minor version >= $MIN_NSIS_MINOR_VER])
+    if test "$MAKENSISU_VER" == "" ||
+       test ! "$MAKENSISU_MAJOR_VER" == "$REQ_NSIS_MAJOR_VER" ||
+       test ! "$MAKENSISU_MINOR_VER" -ge $MIN_NSIS_MINOR_VER; then
+        AC_MSG_RESULT([no])
+        AC_MSG_ERROR([To build the installer you must have the latest MozillaBuild or Unicode NSIS with a major version of $REQ_NSIS_MAJOR_VER and a minimum minor version of $MIN_NSIS_MINOR_VER in your path. To build without the installer reconfigure using --disable-installer.])
+    fi
+    AC_MSG_RESULT([yes])
+    MAKENSISU="${CYGWIN_WRAPPER} $MAKENSISU"
+
     # The Windows build for NSIS requires the iconv command line utility to
     # convert the charset of the locale files.
     MOZ_PATH_PROGS(HOST_ICONV, $HOST_ICONV "iconv", "")
     if test -z "$HOST_ICONV"; then
         AC_MSG_ERROR([To build the installer iconv is required in your path. To build without the installer reconfigure using --disable-installer.])
     fi
 fi
 
@@ -7016,16 +7036,17 @@ dnl win32 options
 AC_SUBST(MOZ_DEBUG_SYMBOLS)
 AC_SUBST(MOZ_MAPINFO)
 AC_SUBST(MOZ_BROWSE_INFO)
 AC_SUBST(MOZ_TOOLS_DIR)
 AC_SUBST(CYGWIN_WRAPPER)
 AC_SUBST(AS_PERL)
 AC_SUBST(WIN32_REDIST_DIR)
 AC_SUBST(PYTHON)
+AC_SUBST(MAKENSISU)
 
 AC_SUBST(WINCE)
 AC_SUBST(WINCE_WINDOWS_MOBILE)
 
 dnl Echo the CFLAGS to remove extra whitespace.
 CFLAGS=`echo \
 	$_WARNINGS_CFLAGS \
 	$CFLAGS`