diff --git a/firefox.spec b/firefox.spec
index 61cc0f1..c50187b 100644
--- a/firefox.spec
+++ b/firefox.spec
@@ -443,6 +443,8 @@ echo "ac_add_options --without-system-icu" >> .mozconfig
 
 %if %{?build_with_rust}
 echo "ac_add_options --enable-rust" >> .mozconfig
+%else
+echo "ac_add_options --disable-rust" >> .mozconfig
 %endif
 
 %ifarch aarch64 ppc64 s390x