diff --git a/App/tools/driver.makefile b/App/tools/driver.makefile
index cb8f1f4..42fc9be 100644
--- a/App/tools/driver.makefile
+++ b/App/tools/driver.makefile
@@ -561,7 +561,7 @@ else # in O.*
 # In O.* directory.
 
 # Add macros like USR_CFLAGS_vxWorks.
-EXTENDED_VARS=INCLUDES CFLAGS CXXFLAGS CPPFLAGS CODE_CXXFLAGS LDFLAGS
+EXTENDED_VARS=INCLUDES CFLAGS CXXFLAGS CPPFLAGS CODE_CXXFLAGS LDFLAGS SYS_LIBS
 $(foreach v,${EXTENDED_VARS},$(foreach x,${VAR_EXTENSIONS},$(eval $v+=$${$v_$x}) $(eval USR_$v+=$${USR_$v_$x})))
 CFLAGS += ${EXTRA_CFLAGS}