diff --git a/config/autoconf.mk.in b/config/autoconf.mk.in
index 9f361aaf0bc..b88ffcbbbac 100644
--- a/config/autoconf.mk.in
+++ b/config/autoconf.mk.in
@@ -177,6 +177,8 @@ JAR="@JAR@"
 
 TAR=@TAR@
 
+MAKENSIS=@MAKENSIS@
+
 RM = rm -f
 
 # The MOZ_UI_LOCALE var is used to build a particular locale. Do *not*
diff --git a/configure.in b/configure.in
index 2fc1d074fe5..81fe836e3e2 100644
--- a/configure.in
+++ b/configure.in
@@ -6428,12 +6428,32 @@ MOZ_ARG_DISABLE_BOOL(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)
+    # 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(MAKENSIS, $MAKENSIS makensisu-2.46 makensisu makensis)
     if test -z "$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.])
+        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 $MIN_NSIS_MINOR_VER in your path. To build without the installer reconfigure using --disable-installer.])
     fi
+    changequote(,)
+    MAKENSIS_VER=`"$MAKENSIS" -version 2>/dev/null | sed -e '/-Unicode/!s/.*//g' -e 's/^v\([0-9]\+\.[0-9]\+\)\-Unicode$/\1/g'`
+    changequote([,])
+    if test ! "$MAKENSIS_VER" == ""; then
+        MAKENSIS_MAJOR_VER=`echo $MAKENSIS_VER | $AWK -F\. '{ print $1 }'`
+        MAKENSIS_MINOR_VER=`echo $MAKENSIS_VER | $AWK -F\. '{ print $2 }'`
+    fi
+    AC_MSG_CHECKING([for Unicode NSIS with major version == $REQ_NSIS_MAJOR_VER and minor version >= $MIN_NSIS_MINOR_VER])
+    if test "$MAKENSIS_VER" == "" ||
+       test ! "$MAKENSIS_MAJOR_VER" == "$REQ_NSIS_MAJOR_VER" ||
+       test ! "$MAKENSIS_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 $MIN_NSIS_MINOR_VER in your path. To build without the installer reconfigure using --disable-installer.])
+    fi
+    AC_MSG_RESULT([yes])
+    MAKENSIS="${CYGWIN_WRAPPER} $MAKENSIS"
+
     # 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", "")
@@ -8693,6 +8713,7 @@ AC_SUBST(CYGWIN_WRAPPER)
 AC_SUBST(AS_PERL)
 AC_SUBST(WIN32_REDIST_DIR)
 AC_SUBST(PYTHON)
+AC_SUBST(MAKENSIS)
 
 AC_SUBST(WINCE)
 AC_SUBST(WINCE_SDK_DIR)
diff --git a/toolkit/mozapps/installer/windows/nsis/makensis.mk b/toolkit/mozapps/installer/windows/nsis/makensis.mk
index 643696f6a41..bc784cff8f1 100644
--- a/toolkit/mozapps/installer/windows/nsis/makensis.mk
+++ b/toolkit/mozapps/installer/windows/nsis/makensis.mk
@@ -68,10 +68,10 @@ $(CONFIG_DIR)/setup.exe::
 	done
 	$(INSTALL) $(addprefix $(MOZILLA_DIR)/toolkit/mozapps/installer/windows/nsis/,$(TOOLKIT_NSIS_FILES)) $(CONFIG_DIR)
 	$(INSTALL) $(MOZILLA_DIR)/toolkit/mozapps/installer/windows/nsis/setup.ico $(CONFIG_DIR)
-	cd $(CONFIG_DIR) && makensisu.exe installer.nsi
+	cd $(CONFIG_DIR) && $(MAKENSIS) installer.nsi
 # Support for building the uninstaller when repackaging locales
 ifeq ($(CONFIG_DIR),l10ngen)
-	cd $(CONFIG_DIR) && makensisu.exe uninstaller.nsi
+	cd $(CONFIG_DIR) && $(MAKENSIS) uninstaller.nsi
 endif
 
 $(CONFIG_DIR)/7zSD.sfx:
@@ -94,6 +94,6 @@ uninstaller::
 	done
 	$(INSTALL) $(addprefix $(MOZILLA_DIR)/toolkit/mozapps/installer/windows/nsis/,$(TOOLKIT_NSIS_FILES)) $(CONFIG_DIR)
 	$(INSTALL) $(MOZILLA_DIR)/toolkit/mozapps/installer/windows/nsis/setup.ico $(CONFIG_DIR)
-	cd $(CONFIG_DIR) && makensisu.exe uninstaller.nsi
+	cd $(CONFIG_DIR) && $(MAKENSIS) uninstaller.nsi
 	$(NSINSTALL) -D $(DIST)/bin/uninstall
 	cp $(CONFIG_DIR)/helper.exe $(DIST)/bin/uninstall