diff --git a/configs/mx1ads/ostest/Make.defs b/configs/mx1ads/ostest/Make.defs
index f0fa333666..055e4c89fc 100644
--- a/configs/mx1ads/ostest/Make.defs
+++ b/configs/mx1ads/ostest/Make.defs
@@ -67,6 +67,7 @@ else
 endif
 ARCHDEFINES		=
 ARCHINCLUDES		= -I. -isystem $(TOPDIR)/include
+ARCHXXINCLUDES		= -I. -isystem $(TOPDIR)/include -isystem $(TOPDIR)/include/cxx
 
 ARCHPICFLAGS		= -fpic
 ARCHSCRIPT		= -T$(TOPDIR)/configs/$(CONFIG_ARCH_BOARD)/ostest/ld.script
@@ -74,7 +75,7 @@ ARCHSCRIPT		= -T$(TOPDIR)/configs/$(CONFIG_ARCH_BOARD)/ostest/ld.script
 CFLAGS			= $(ARCHCFLAGS) $(ARCHWARNINGS) $(ARCHOPTIMIZATION) \
 			  $(ARCHCPUFLAGS) $(ARCHINCLUDES) $(ARCHDEFINES) -pipe
 CXXFLAGS		= $(ARCHCXXFLAGS) $(ARCHWARNINGSXX) $(ARCHOPTIMIZATION) \
-			  $(ARCHCPUFLAGS) $(ARCHINCLUDES) $(ARCHDEFINES) -pipe
+			  $(ARCHCPUFLAGS) $(ARCHXXINCLUDES) $(ARCHDEFINES) -pipe
 CPPFLAGS		= $(ARCHINCLUDES) $(ARCHDEFINES)
 AFLAGS			= $(CFLAGS) -D__ASSEMBLY__