--- a/media/libcubeb/src/moz.build
+++ b/media/libcubeb/src/moz.build
@@ -83,12 +83,13 @@ if CONFIG['OS_TARGET'] == 'Android':
     SOURCES += [
         'cubeb_audiotrack.c',
     ]
     DEFINES['USE_AUDIOTRACK'] = True
 
 FINAL_LIBRARY = 'gkmedias'
 
 CFLAGS += CONFIG['MOZ_ALSA_CFLAGS']
+CFLAGS += CONFIG['MOZ_JACK_CFLAGS']
 CFLAGS += CONFIG['MOZ_PULSEAUDIO_CFLAGS']
 
 # We allow warnings for third-party code that can be updated from upstream.
 AllowCompilerWarnings()

--- a/toolkit/moz.configure
+++ b/toolkit/moz.configure
@@ -55,23 +55,20 @@ imply_option('--enable-profiling', dmd)
 imply_option('--enable-jemalloc', dmd)
 imply_option('--enable-replace-malloc', dmd)
 
 # JACK cubeb backend
 # ==============================================================
 option('--enable-jack', env='MOZ_JACK',
        help='Enable JACK audio backend.')
 
-@depends('--enable-jack')
-def jack(value):
-    if value:
-        return True
+jack = pkg_check_modules('MOZ_JACK', 'jack', when='--enable-jack')
 
-set_config('MOZ_JACK', jack)
-set_define('MOZ_JACK', jack)
+set_config('MOZ_JACK', depends_if(jack)(lambda _: True))
+set_define('MOZ_JACK', depends_if(jack)(lambda _: True))
 
 # Javascript engine
 # ==============================================================
 include('../js/moz.configure')
 
 
 # Rust
 # ==============================================================