--- a/media/webrtc/moz.build
+++ b/media/webrtc/moz.build
@@ -47,16 +47,17 @@ if CONFIG['MOZ_WEBRTC_SIGNALING']:
     GYP_DIRS += ['signaling']
     GYP_DIRS['signaling'].input = 'signaling/signaling.gyp'
     GYP_DIRS['signaling'].variables = gyp_vars.copy()
     GYP_DIRS['signaling'].variables.update(
         build_for_test=0,
         build_for_standalone=0
     )
     GYP_DIRS['signaling'].sandbox_vars['FINAL_LIBRARY'] = 'xul'
+    GYP_DIRS['signaling'].sandbox_vars['FAIL_ON_WARNINGS'] = True
     # Excluded for various symbol conflicts
     signaling_non_unified_sources = [
         'signaling/src/common/browser_logging/CSFLog.cpp',
         'signaling/src/jsep/JsepSessionImpl.cpp',
         'signaling/src/media-conduit/AudioConduit.cpp',
         'signaling/src/media-conduit/CodecStatistics.cpp',
         'signaling/src/media-conduit/MediaCodecVideoCodec.cpp',
         'signaling/src/media-conduit/VideoConduit.cpp',
@@ -95,16 +96,19 @@ if CONFIG['MOZ_WIDGET_TOOLKIT'] != 'gonk
         GYP_DIRS['signalingtest'].input = 'signaling/signaling.gyp'
         GYP_DIRS['signalingtest'].variables = gyp_vars.copy()
         GYP_DIRS['signalingtest'].variables.update(
             build_for_test=1,
             moz_webrtc_mediacodec=0,
             build_for_standalone=0
         )
         GYP_DIRS['signalingtest'].non_unified_sources += signaling_non_unified_sources
+        GYP_DIRS['signalingtest'].sandbox_vars['FAIL_ON_WARNINGS'] = True
+
         GYP_DIRS += ['signalingstandalone']
         GYP_DIRS['signalingstandalone'].input = 'signaling/signaling.gyp'
         GYP_DIRS['signalingstandalone'].variables = gyp_vars.copy()
         GYP_DIRS['signalingstandalone'].variables.update(
             build_for_test=0,
             build_for_standalone=1
         )
         GYP_DIRS['signalingstandalone'].non_unified_sources += signaling_non_unified_sources
+        GYP_DIRS['signalingstandalone'].sandbox_vars['FAIL_ON_WARNINGS'] = True

--- a/media/webrtc/signaling/signaling.gyp
+++ b/media/webrtc/signaling/signaling.gyp
@@ -196,17 +196,16 @@
         'HAVE_UINT32_T=1',
         'HAVE_UINT64_T=1',
       ],
 
       'cflags_mozilla': [
         '$(NSPR_CFLAGS)',
         '$(NSS_CFLAGS)',
         '$(MOZ_PIXMAN_CFLAGS)',
-        '$(WARNINGS_AS_ERRORS)',
       ],
 
 
       #
       # Conditionals
       #
       'conditions': [
         # hack so I can change the include flow for SrtpFlow