diff --git a/lib/Makefile b/lib/Makefile
index ebf7a981db00..efe07f7ef5a1 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -131,7 +131,7 @@ SUBDIR_DEPEND_libarchive= libz libbz2 libexpat liblzma libmd
 SUBDIR_DEPEND_libatm= libmd
 SUBDIR_DEPEND_libauditdm= libbsm
 SUBDIR_DEPEND_libbsnmp= ${_libnetgraph}
-SUBDIR_DEPEND_libc++= libcxxrt
+SUBDIR_DEPEND_libc++:= libcxxrt
 SUBDIR_DEPEND_libc= libcompiler_rt
 SUBDIR_DEPEND_libcam= libsbuf
 SUBDIR_DEPEND_libcapsicum= libnv