diff --git a/lib/libproc/Makefile b/lib/libproc/Makefile
index 4449c0642542..5b1df7432f64 100644
--- a/lib/libproc/Makefile
+++ b/lib/libproc/Makefile
@@ -14,6 +14,8 @@ SRCS=	proc_bkpt.c		\
 INCS=	libproc.h
 
 CFLAGS+=	-I${.CURDIR}
+# avoid cyclic dependency
+CFLAGS+=	-I${.CURDIR:H}/librtld_db
 
 .if ${MK_LIBCPLUSPLUS} != "no"
 LDADD+=		-lcxxrt