diff --git a/libsrc/Makefile b/libsrc/Makefile
index 89f952376..99da96f1e 100644
--- a/libsrc/Makefile
+++ b/libsrc/Makefile
@@ -91,7 +91,7 @@ endef
 else # TARGET
 
 CA65FLAGS =
-CC65FLAGS = -Osir -W error
+CC65FLAGS = -Or -W error
 
 EXTZP = cbm510 \
         cbm610 \
diff --git a/libsrc/atari/targetutil/Makefile.inc b/libsrc/atari/targetutil/Makefile.inc
index a54d96100..fc91f96a9 100644
--- a/libsrc/atari/targetutil/Makefile.inc
+++ b/libsrc/atari/targetutil/Makefile.inc
@@ -2,7 +2,6 @@ ifeq ($(TARGET),atari)
 
 DEPS += ../wrk/$(TARGET)/w2cas.d
 
-../wrk/$(TARGET)/w2cas.o: CC65FLAGS:=-O -W error
 ../wrk/$(TARGET)/w2cas.o: $(SRCDIR)/targetutil/w2cas.c | ../wrk/$(TARGET)
 	$(COMPILE_recipe)