--- a/config/external/nss/Makefile.in
+++ b/config/external/nss/Makefile.in
@@ -234,16 +234,17 @@ endif
 ifneq (,$(NSS_EXTRA_LDFLAGS))
 DEFAULT_GMAKE_FLAGS += \
 	LDFLAGS='$(LDFLAGS) $(NSS_EXTRA_LDFLAGS)' \
 	DSO_LDOPTS='$(DSO_LDOPTS) $(LDFLAGS) $(NSS_EXTRA_LDFLAGS)' \
 	$(NULL)
 endif
 
 DEFAULT_GMAKE_FLAGS += FREEBL_NO_DEPEND=0 $(FREEBL_LOWHASH_FLAG)
+DEFAULT_GMAKE_FLAGS += NSS_ALLOW_SSLKEYLOGFILE=1
 
 ifdef MOZ_NO_WLZDEFS
 DEFAULT_GMAKE_FLAGS += ZDEFS_FLAG=
 endif
 ifdef MOZ_CFLAGS_NSS
 DEFAULT_GMAKE_FLAGS += XCFLAGS='$(filter-out -W%,$(CFLAGS))'
 DEFAULT_GMAKE_FLAGS += DARWIN_DYLIB_VERSIONS='-compatibility_version 1 -current_version 1 $(LDFLAGS)'
 endif