diff --git a/media/libaom/moz.build b/media/libaom/moz.build
index 4a3518acbe64..fd8c7f2b3388 100644
--- a/media/libaom/moz.build
+++ b/media/libaom/moz.build
@@ -13,7 +13,7 @@ include('sources.mozbuild')
 if CONFIG['CPU_ARCH'] == 'x86_64':
     EXPORTS.aom += files['X64_EXPORTS']
     SOURCES += files['X64_SOURCES']
-    USE_YASM = True
+    USE_NASM = True
     if CONFIG['OS_TARGET'] == 'WINNT':
         ASFLAGS += [ '-I%s/media/libaom/config/win/x64/' % TOPSRCDIR ]
         LOCAL_INCLUDES += [ '/media/libaom/config/win/x64/' ]
@@ -32,7 +32,7 @@ if CONFIG['CPU_ARCH'] == 'x86_64':
 elif CONFIG['CPU_ARCH'] == 'x86':
     EXPORTS.aom += files['IA32_EXPORTS']
     SOURCES += files['IA32_SOURCES']
-    USE_YASM = True
+    USE_NASM = True
     if CONFIG['OS_TARGET'] == 'WINNT':
         ASFLAGS += [ '-I%s/media/libaom/config/win/ia32/' % TOPSRCDIR ]
         LOCAL_INCLUDES += [ '/media/libaom/config/win/ia32/' ]
diff --git a/media/libaom/sources.mozbuild b/media/libaom/sources.mozbuild
index cab5e130b1d7..672d48bf24d2 100644
--- a/media/libaom/sources.mozbuild
+++ b/media/libaom/sources.mozbuild
@@ -276,7 +276,6 @@ files = {
     '../../third_party/aom/aom_dsp/x86/loopfilter_sse2.c',
     '../../third_party/aom/aom_mem/aom_mem.c',
     '../../third_party/aom/aom_ports/emms.asm',
-    '../../third_party/aom/aom_ports/x86_abi_support.asm',
     '../../third_party/aom/aom_scale/aom_scale_rtcd.c',
     '../../third_party/aom/aom_scale/generic/aom_scale.c',
     '../../third_party/aom/aom_scale/generic/gen_scalers.c',