diff --git a/config/mh-mingw b/config/mh-mingw
index e91367a7112..f5fb064813f 100644
--- a/config/mh-mingw
+++ b/config/mh-mingw
@@ -1,7 +1,6 @@
 # Add -D__USE_MINGW_ACCESS to enable the built compiler to work on Windows
 # Vista (see PR33281 for details).
 BOOT_CFLAGS += -D__USE_MINGW_ACCESS -Wno-pedantic-ms-format
-BOOT_CXXFLAGS += -D__USE_MINGW_ACCESS -Wno-pedantic-ms-format
 CFLAGS += -D__USE_MINGW_ACCESS
 CXXFLAGS += -D__USE_MINGW_ACCESS
 STAGE1_CXXFLAGS += -D__USE_MINGW_ACCESS