diff -up firefox-71.0/old-configure.in.nss-version firefox-71.0/old-configure.in
--- firefox-71.0/old-configure.in.nss-version	2019-11-25 15:15:15.767572575 +0100
+++ firefox-71.0/old-configure.in	2019-11-25 15:16:47.363498527 +0100
@@ -1512,7 +1512,7 @@ MOZ_ARG_WITH_BOOL(system-nss,
     _USE_SYSTEM_NSS=1 )
 
 if test -n "$_USE_SYSTEM_NSS"; then
-    AM_PATH_NSS(3.47.1, [MOZ_SYSTEM_NSS=1], [AC_MSG_ERROR([you don't have NSS installed or your version is too old])])
+    AM_PATH_NSS(3.47.0, [MOZ_SYSTEM_NSS=1], [AC_MSG_ERROR([you don't have NSS installed or your version is too old])])
 fi
 
 NSS_CFLAGS="$NSS_CFLAGS -I${DIST}/include/nss"