--- a/b2g/confvars.sh
+++ b/b2g/confvars.sh
@@ -21,17 +21,16 @@ MOZ_SAFE_BROWSING=1
 
 MOZ_NO_SMART_CARDS=1
 MOZ_APP_STATIC_INI=1
 MOZ_NO_EV_CERTS=1
 
 MOZ_WEBSPEECH=1
 if test -n "$NIGHTLY_BUILD"; then
 MOZ_WEBSPEECH_MODELS=1
-MOZ_WEBSPEECH_POCKETSPHINX=1
 fi
 MOZ_WEBSPEECH_TEST_BACKEND=1
 
 if test "$OS_TARGET" = "Android"; then
 MOZ_CAPTURE=1
 MOZ_RAW=1
 MOZ_AUDIO_CHANNEL_MANAGER=1
 fi

--- a/old-configure.in
+++ b/old-configure.in
@@ -2331,17 +2331,16 @@ MOZ_WEBRTC_SIGNALING=
 MOZ_WEBRTC_ASSERT_ALWAYS=1
 MOZ_WEBRTC_HARDWARE_AEC_NS=
 MOZ_SCTP=
 MOZ_ANDROID_OMX=
 MOZ_OMX_PLUGIN=
 MOZ_VPX_ERROR_CONCEALMENT=
 MOZ_WEBSPEECH=1
 MOZ_WEBSPEECH_MODELS=
-MOZ_WEBSPEECH_POCKETSPHINX=
 MOZ_WEBSPEECH_TEST_BACKEND=1
 VPX_USE_YASM=
 VPX_ASFLAGS=
 VPX_AS_CONVERSION=
 VPX_X86_ASM=
 VPX_ARM_ASM=
 LIBJPEG_TURBO_AS=
 LIBJPEG_TURBO_ASFLAGS=
@@ -3003,25 +3002,16 @@ if test "$OS_TARGET" = "Android" -o "$CP
     AC_SUBST(MOZ_SAMPLE_TYPE_S16)
 else
     MOZ_SAMPLE_TYPE_FLOAT32=1
     AC_DEFINE(MOZ_SAMPLE_TYPE_FLOAT32)
     AC_SUBST(MOZ_SAMPLE_TYPE_FLOAT32)
 fi
 
 dnl ========================================================
-dnl = Disable Speech API pocketsphinx backend
-dnl ========================================================
-if test -n "$MOZ_WEBSPEECH_POCKETSPHINX"; then
-    AC_DEFINE(MOZ_WEBSPEECH_POCKETSPHINX)
-fi
-
-AC_SUBST(MOZ_WEBSPEECH_POCKETSPHINX)
-
-dnl ========================================================
 dnl = Disable Speech API code
 dnl ========================================================
 MOZ_ARG_DISABLE_BOOL(webspeech,
 [  --disable-webspeech        Disable support for HTML Speech API],
     MOZ_WEBSPEECH=,
     MOZ_WEBSPEECH=1)
 
 if test -n "$MOZ_WEBSPEECH"; then

--- a/toolkit/moz.configure
+++ b/toolkit/moz.configure
@@ -536,16 +536,26 @@ def no_speechd_on_non_gtk(toolkit):
 imply_option('--enable-synth-speechd', no_speechd_on_non_gtk,
              reason='--enable-default-toolkit')
 
 option('--disable-synth-speechd', help='Disable speech-dispatcher support')
 
 set_config('MOZ_SYNTH_SPEECHD',
            depends_if('--disable-synth-speechd')(lambda _: True))
 
+# Speech API pocketsphinx backend
+# ==============================================================
+@depends(build_project, milestone)
+def webspeech_pocketsphinx(build_project, milestone):
+    if milestone.is_nightly and build_project == 'b2g':
+        return True
+
+set_config('MOZ_WEBSPEECH_POCKETSPHINX', webspeech_pocketsphinx)
+set_define('MOZ_WEBSPEECH_POCKETSPHINX', webspeech_pocketsphinx)
+
 # WebSMS
 # ==============================================================
 @depends(build_project, '--help')
 def websms_default(build_project, _):
     return build_project in ('b2g', 'b2g/graphene')
 
 option('--enable-websms-backend', default=websms_default,
        help='Enable WebSMS backend')