diff --git a/share/mk/src.libnames.mk b/share/mk/src.libnames.mk
--- a/share/mk/src.libnames.mk
+++ b/share/mk/src.libnames.mk
@@ -513,6 +513,12 @@
 DPADD_gtest_main+=	${DPADD_gtest}
 LDADD_gtest_main+=	${LDADD_gtest}
 
+# libcasper helpers are in /lib/casper which is not in the default library
+# search path.
+.for cap in dns fileargs grp net pwd sysctl syslog
+LDADD_cap_${cap}+= -Wl,-rpath,/lib/casper
+.endfor
+
 # Detect LDADD/DPADD that should be LIBADD, before modifying LDADD here.
 _BADLDADD=
 .for _l in ${LDADD:M-l*:N-l*/*:C,^-l,,}