diff --git a/configure/os/CONFIG.Common.win32-x86-mingw b/configure/os/CONFIG.Common.win32-x86-mingw
index 5bc450d64..b2ad7ad2b 100644
--- a/configure/os/CONFIG.Common.win32-x86-mingw
+++ b/configure/os/CONFIG.Common.win32-x86-mingw
@@ -15,8 +15,6 @@ ARCH_CLASS = x86
 
 EXE=.exe
 
-POSIX_CPPFLAGS = -D_POSIX_SOURCE
-
 ARCH_DEP_CPPFLAGS += -D_X86_
 
 # Library used when COMMANDLINE_LIBRARY is READLINE