deleted file mode 100644
--- a/accessible/windows/ia2/Makefile.in
+++ /dev/null
@@ -1,9 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-# The midl generated code include Windows headers which defines min and max
-# macros which conflicts with std::min/max.  Suppress the macros:
-OS_CXXFLAGS += -DNOMINMAX
-
-include $(topsrcdir)/config/rules.mk

--- a/accessible/windows/ia2/moz.build
+++ b/accessible/windows/ia2/moz.build
@@ -40,8 +40,13 @@ LOCAL_INCLUDES += [
     '/accessible/generic',
     '/accessible/html',
     '/accessible/windows/msaa',
     '/accessible/xpcom',
     '/accessible/xul',
 ]
 
 FINAL_LIBRARY = 'xul'
+
+# The midl generated code include Windows headers which defines min and max
+# macros which conflicts with std::min/max.  Suppress the macros:
+if CONFIG['OS_ARCH'] == 'WINNT':
+    DEFINES['NOMINMAX'] = True

deleted file mode 100644
--- a/accessible/windows/uia/Makefile.in
+++ /dev/null
@@ -1,9 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-# The midl generated code include Windows headers which defines min and max
-# macros which conflicts with std::min/max.  Suppress the macros:
-OS_CXXFLAGS += -DNOMINMAX
-
-include $(topsrcdir)/config/rules.mk

--- a/accessible/windows/uia/moz.build
+++ b/accessible/windows/uia/moz.build
@@ -13,8 +13,13 @@ LOCAL_INCLUDES += [
     '/accessible/generic',
     '/accessible/html',
     '/accessible/windows/msaa',
     '/accessible/xpcom',
     '/accessible/xul',
 ]
 
 FINAL_LIBRARY = 'xul'
+
+# The midl generated code include Windows headers which defines min and max
+# macros which conflicts with std::min/max.  Suppress the macros:
+if CONFIG['OS_ARCH'] == 'WINNT':
+    DEFINES['NOMINMAX'] = True

deleted file mode 100644
--- a/content/media/directshow/Makefile.in
+++ /dev/null
@@ -1,7 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-ifeq ($(OS_ARCH),WINNT)
-OS_CXXFLAGS += -DNOMINMAX
-endif

--- a/content/media/directshow/moz.build
+++ b/content/media/directshow/moz.build
@@ -37,8 +37,10 @@ if not CONFIG['MOZ_WEBRTC']:
 
 FAIL_ON_WARNINGS = True
 
 FINAL_LIBRARY = 'xul'
 LOCAL_INCLUDES += [
     '/media/webrtc/trunk/webrtc/modules/video_capture/windows',
 ]
 
+if CONFIG['OS_ARCH'] == 'WINNT':
+    DEFINES['NOMINMAX'] = True

deleted file mode 100644
--- a/content/media/fmp4/Makefile.in
+++ /dev/null
@@ -1,7 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-ifeq ($(OS_ARCH),WINNT)
-OS_CXXFLAGS += -DNOMINMAX
-endif

--- a/content/media/fmp4/moz.build
+++ b/content/media/fmp4/moz.build
@@ -56,8 +56,11 @@ if CONFIG['MOZ_APPLEMEDIA']:
   ]
   LDFLAGS += [
       '-framework AudioToolbox',
   ]
 
 FINAL_LIBRARY = 'xul'
 
 FAIL_ON_WARNINGS = True
+
+if CONFIG['OS_ARCH'] == 'WINNT':
+    DEFINES['NOMINMAX'] = True

deleted file mode 100644
--- a/content/media/wmf/Makefile.in
+++ /dev/null
@@ -1,7 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-ifeq ($(OS_ARCH),WINNT)
-OS_CXXFLAGS += -DNOMINMAX
-endif

--- a/content/media/wmf/moz.build
+++ b/content/media/wmf/moz.build
@@ -22,8 +22,11 @@ UNIFIED_SOURCES += [
 
 SOURCES += [
     'WMFUtils.cpp',
 ]
 
 FAIL_ON_WARNINGS = True
 
 FINAL_LIBRARY = 'xul'
+
+if CONFIG['OS_ARCH'] == 'WINNT':
+    DEFINES['NOMINMAX'] = True