diff --git a/firefox.spec b/firefox.spec
index 38b2727..6b0efb6 100644
--- a/firefox.spec
+++ b/firefox.spec
@@ -228,7 +228,9 @@ Files and macros mainly for building Firefox extensions.
 
 %patch219 -p1 -b .ntlm
 
+%if %{with system_nss_nspr}
 %patch300 -p1
+%endif
 %patch302 -p1
 
 pushd js/src