--- a/toolkit/crashreporter/crashreporter.mozbuild
+++ b/toolkit/crashreporter/crashreporter.mozbuild
@@ -25,17 +25,21 @@ elif CONFIG['GNU_CXX']:
         '-Wno-unused-local-typedefs',
         '-Wno-shadow',
         '-Wno-deprecated-declarations',
         '-Wno-bool-compare',
         '-Wno-unused-but-set-variable',
     ]
 
 if CONFIG['CLANG_CXX'] or CONFIG['CLANG_CL']:
-    CXXFLAGS += [
-        '-Wno-implicit-fallthrough',
-        '-Wno-c++11-narrowing',
-    ]
+     CXXFLAGS += [
+         '-Wno-c++11-narrowing',
+     ]
+
+if not CONFIG['_MSC_VER']:
+     CXXFLAGS += [
+         '-Wno-implicit-fallthrough',
+     ]
 
 if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'gonk':
     DEFINES['ELFSIZE'] = 32
 
 DEFINES['NO_STABS_SUPPORT'] = True