diff -urN qtbase.orig/mkspecs/macx-clang/qmake.conf qtbase/mkspecs/macx-clang/qmake.conf
--- qtbase.orig/mkspecs/macx-clang/qmake.conf	2018-02-13 11:08:52.000000000 +0000
+++ qtbase/mkspecs/macx-clang/qmake.conf	2018-02-13 11:10:31.000000000 +0000
@@ -2,7 +2,7 @@
 # qmake configuration for Clang on OS X
 #
 
-QMAKE_MACOSX_DEPLOYMENT_TARGET = 10.10
+QMAKE_MACOSX_DEPLOYMENT_TARGET = 10.9
 
 QMAKE_APPLE_DEVICE_ARCHS = x86_64
 
diff -urN qtbase.orig/mkspecs/macx-g++/qmake.conf qtbase/mkspecs/macx-g++/qmake.conf
--- qtbase.orig/mkspecs/macx-g++/qmake.conf	2018-02-13 11:08:52.000000000 +0000
+++ qtbase/mkspecs/macx-g++/qmake.conf	2018-02-13 11:10:51.000000000 +0000
@@ -10,7 +10,7 @@
 CONFIG                 += app_bundle incremental global_init_link_order lib_version_first
 QMAKE_INCREMENTAL_STYLE = sublib
 
-QMAKE_MACOSX_DEPLOYMENT_TARGET = 10.10
+QMAKE_MACOSX_DEPLOYMENT_TARGET = 10.9
 
 QMAKE_APPLE_DEVICE_ARCHS = x86_64
 
diff -urN qtbase.orig/mkspecs/macx-icc/qmake.conf qtbase/mkspecs/macx-icc/qmake.conf
--- qtbase.orig/mkspecs/macx-icc/qmake.conf	2018-02-13 11:08:52.000000000 +0000
+++ qtbase/mkspecs/macx-icc/qmake.conf	2018-02-13 11:10:42.000000000 +0000
@@ -95,7 +95,7 @@
 QMAKE_CFLAGS_HIDESYMS   += -fvisibility=hidden
 QMAKE_CXXFLAGS_HIDESYMS += $$QMAKE_CFLAGS_HIDESYMS -fvisibility-inlines-hidden
 
-QMAKE_MACOSX_DEPLOYMENT_TARGET = 10.10
+QMAKE_MACOSX_DEPLOYMENT_TARGET = 10.9
 
 QMAKE_APPLE_DEVICE_ARCHS = x86_64