diff --git a/src/test/run-make-fulldeps/reproducible-build/Makefile b/src/test/run-make-fulldeps/reproducible-build/Makefile
index 5b9c9d3d0352..addbf9928bf4 100644
--- a/src/test/run-make-fulldeps/reproducible-build/Makefile
+++ b/src/test/run-make-fulldeps/reproducible-build/Makefile
@@ -81,7 +81,7 @@ extern_flags:
 fat_lto:
 	rm -rf $(TMPDIR) && mkdir $(TMPDIR)
 	$(RUSTC) reproducible-build-aux.rs
-	$(RUSTC) reproducible-build.rs -C lto=fat
+	$(RUSTC) reproducible-build.rs -C lto=fat -C opt-level=1
 	cp $(TMPDIR)/reproducible-build $(TMPDIR)/reproducible-build-a
-	$(RUSTC) reproducible-build.rs -C lto=fat
+	$(RUSTC) reproducible-build.rs -C lto=fat -C opt-level=1
 	cmp "$(TMPDIR)/reproducible-build-a" "$(TMPDIR)/reproducible-build" || exit 1