diff --git a/debian/rules b/debian/rules
index d2f9724..bd4003a 100755
--- a/debian/rules
+++ b/debian/rules
@@ -1,11 +1,11 @@
 #!/usr/bin/make -f
 
-export PIKA_BUILD_ARCH = $(shell cat pika-build-arch)
+export PIKA_BUILD_ARCH = $(shell cat ../pika-build-arch)
 
 override_dh_prep:
 # amd64 build prep
 ifeq (amd64-v3,$(PIKA_BUILD_ARCH))
-	export RUSTFLAGS  = "-C target-cpu=x86-64-v3"
+export RUSTFLAGS = -C target-cpu=x86-64-v3 -C opt-level=3 -C lto=fat -C embed-bitcode -C codegen-units=1
 endif
 
 %: