diff --git a/share/mk/bsd.prog.mk b/share/mk/bsd.prog.mk
index c8f2f723c834..4de78cb921e2 100644
--- a/share/mk/bsd.prog.mk
+++ b/share/mk/bsd.prog.mk
@@ -17,6 +17,7 @@ NO_WERROR=
 
 .if defined(DEBUG_FLAGS)
 CFLAGS+=${DEBUG_FLAGS}
+CXXFLAGS+=${DEBUG_FLAGS}
 
 .if !defined(NO_CTF) && (${DEBUG_FLAGS:M-g} != "")
 CTFFLAGS+= -g