diff --git a/configure/os/CONFIG.Common.RTEMS b/configure/os/CONFIG.Common.RTEMS
index a26dc0ec9..ffb5a0a67 100644
--- a/configure/os/CONFIG.Common.RTEMS
+++ b/configure/os/CONFIG.Common.RTEMS
@@ -75,7 +75,6 @@ OS_CLASS = RTEMS
 
 #--------------------------------------------------
 # Operating system flags
-OP_SYS_CPPFLAGS = -Dmain=rtems_main
 OP_SYS_LDLIBS = -lrtemscpu -lrtemsCom -lreadline -lcurses -lm
 OP_SYS_LDFLAGS = $(CPU_CFLAGS) -u Init \
                  $(PROJECT_RELEASE)/lib/no-dpmem.rel \