diff --git a/GNUmakefile b/GNUmakefile
index 0d30e88..e3be6be 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -15,9 +15,12 @@
 .PHONY: test
 
 PREFIX=/usr/local
+
 CC=cc
 CFLAGS=-O3 -Lbuild/lib
+
 RUSTC=rustc
+RUSTCFLAGS=-C opt-level=z -C codegen-units=1 -C panic=abort -C lto=y -C strip=symbols
 
 ifeq ($(CC), gcc)
 	CFLAGS=-O3 -s -Wl,-z,noseparate-code,-z,nosectionheader -flto \
@@ -53,7 +56,7 @@ test: build
 	tests/posix-compat.sh
 
 false: src/false.rs build_dir
-	$(RUSTC) -o build/bin/false src/false.rs
+	$(RUSTC) $(RUSTCFLAGS) -o build/bin/false src/false.rs
 
 intcmp: src/intcmp.c build_dir
 	$(CC) $(CFLAGS) -o build/bin/intcmp src/intcmp.c
@@ -67,8 +70,8 @@ str: src/str.c build_dir
 strcmp: src/strcmp.c build_dir
 	$(CC) $(CFLAGS) -o build/bin/strcmp src/strcmp.c
 
-true: src/true.c build_dir
-	$(CC) $(CFLAGS) -o build/bin/true src/true.c
+true: src/true.rs build_dir
+	$(RUSTC) $(RUSTCFLAGS) -o build/bin/true src/true.rs
 
 libfileis: src/libfileis.c src/libfileis.h build_dir
 	$(CC) $(CFLAGS) -c -fPIC -o build/o/libfileis.o src/libfileis.c