--- a/build/moz.configure/old.configure
+++ b/build/moz.configure/old.configure
@@ -165,17 +165,16 @@ def old_configure_options(*options):
     return depends(prepare_configure, extra_old_configure_args, all_options,
                    *options)
 
 
 @old_configure_options(
     '--cache-file',
     '--datadir',
     '--enable-accessibility',
-    '--enable-alsa',
     '--enable-bundled-fonts',
     '--enable-content-sandbox',
     '--enable-cookies',
     '--enable-cpp-rtti',
     '--enable-crashreporter',
     '--enable-dbus',
     '--enable-debug-js-modules',
     '--enable-directshow',

--- a/old-configure.in
+++ b/old-configure.in
@@ -2594,34 +2594,16 @@ fi
 if test -n "$MOZ_TREMOR"; then
     AC_DEFINE(MOZ_TREMOR)
 fi
 
 MOZ_WEBM_ENCODER=1
 AC_DEFINE(MOZ_WEBM_ENCODER)
 AC_SUBST(MOZ_WEBM_ENCODER)
 
-dnl ==================================
-dnl = Check alsa availability on Linux
-dnl ==================================
-
-MOZ_ARG_ENABLE_BOOL(alsa,
-[  --enable-alsa          Enable Alsa support],
-   MOZ_ALSA=1,
-   MOZ_ALSA=)
-
-if test -n "$MOZ_ALSA"; then
-    AC_DEFINE(MOZ_ALSA)
-    PKG_CHECK_MODULES(MOZ_ALSA, alsa, ,
-         [echo "$MOZ_ALSA_PKG_ERRORS"
-          AC_MSG_ERROR([Need alsa for audio output on Linux. (On Ubuntu, you might try installing the package libasound2-dev.)])])
-fi
-
-AC_SUBST(MOZ_ALSA)
-
 dnl ========================================================
 dnl = Disable PulseAudio
 dnl ========================================================
 
 dnl If using Desktop Linux, ensure that the PA library is available
 case "$OS_TARGET" in
 WINNT|Darwin|Android|OpenBSD)
     ;;

--- a/toolkit/moz.configure
+++ b/toolkit/moz.configure
@@ -50,16 +50,26 @@ def dmd(value):
 
 set_config('MOZ_DMD', dmd)
 set_define('MOZ_DMD', dmd)
 add_old_configure_assignment('MOZ_DMD', dmd)
 imply_option('--enable-profiling', dmd)
 imply_option('--enable-jemalloc', dmd)
 imply_option('--enable-replace-malloc', dmd)
 
+# ALSA cubeb backend
+# ==============================================================
+option('--enable-alsa', env='MOZ_ALSA',
+       help='Enable ALSA audio backend.')
+
+alsa = pkg_check_modules('MOZ_ALSA', 'alsa', when='--enable-alsa')
+
+set_config('MOZ_ALSA', depends_if(alsa)(lambda _: True))
+set_define('MOZ_ALSA', depends_if(alsa)(lambda _: True))
+
 # JACK cubeb backend
 # ==============================================================
 option('--enable-jack', env='MOZ_JACK',
        help='Enable JACK audio backend.')
 
 jack = pkg_check_modules('MOZ_JACK', 'jack', when='--enable-jack')
 
 set_config('MOZ_JACK', depends_if(jack)(lambda _: True))