--- a/mfbt/moz.build
+++ b/mfbt/moz.build
@@ -136,19 +136,21 @@ DEFINES['IMPL_MFBT'] = True
 SOURCES += mfbt_nonunified_src_cppsrcs
 
 DisableStlWrapping()
 
 # Suppress warnings in third-party LZ4 code.
 # TODO: Remove these suppressions after bug 993267 is fixed.
 
 if CONFIG['GNU_CXX']:
-    SOURCES['/mfbt/Compression.cpp'].flags += ['-Wno-unused-function']
+    SOURCES['/mfbt/Compression.cpp'].flags += ['-Wno-unused-function',
+                                               '-Wno-deprecated-register']
     CXXFLAGS += ['-Wno-error=shadow']
 
+
 if CONFIG['CLANG_CXX']:
     # Suppress warnings from third-party V8 Decimal code.
     SOURCES['/mfbt/decimal/Decimal.cpp'].flags += ['-Wno-implicit-fallthrough']
 
 if CONFIG['_MSC_VER']:
     # Error 4804 is "'>' : unsafe use of type 'bool' in operation"
     SOURCES['/mfbt/Compression.cpp'].flags += ['-wd4804']