diff --git a/js/src/config/rules.mk b/js/src/config/rules.mk
index 90db46bce0a..f6fe93ab073 100644
--- a/js/src/config/rules.mk
+++ b/js/src/config/rules.mk
@@ -197,7 +197,7 @@ ifdef CPP_UNIT_TESTS
 CPPSRCS += $(CPP_UNIT_TESTS)
 SIMPLE_PROGRAMS += $(CPP_UNIT_TESTS:.cpp=$(BIN_SUFFIX))
 REQUIRES += testing xpcom
-LIBS += $(XPCOM_LIBS) $(XPCOM_GLUE_LDOPTS) $(NSPR_LIBS)
+LIBS += $(XPCOM_GLUE_LDOPTS) $(NSPR_LIBS)
 
 # ...and run them the usual way
 check::