diff --git a/GNUmakefile b/GNUmakefile
index da8a673..7722d7f 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -65,8 +65,8 @@ sysexits: build_dir
 		> build/include/sysexits.h 
 	bindgen --default-macro-constant-type signed --use-core \
 		"$$(printf '#include <sysexits.h>\n' \
-		| cpp -M -idirafter "$$PWD/build/include" - \
-		| sed 's/ /\n/g' | grep sysexits.h)" \
+			| cpp -M -idirafter "build/include" - \
+			| sed 's/ /\n/g' | grep sysexits.h)" \
 		| $(RUSTC) $(RUSTCFLAGS) --crate-type lib -o build/o/libsysexits.rlib -
 
 false: src/false.rs build_dir