diff --git a/Makefile b/Makefile
index 6b1ed80..6fadc8c 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,12 @@
 # Set the TARGETS and PROGRAM values as required.
 # See makefiles/build.mk for details on directory structure for src files and how to add custom extensions to the build.
 
-TARGETS = adam apple2 apple2enh atari c64 coco msdos
+# Require GNU Make 4.0 or later for $(file ...) function
+ifeq ($(filter 4.%,$(MAKE_VERSION)),)
+    $(error This Makefile requires GNU Make 4.0 or later. You are using $(MAKE_VERSION). Please use 'gmake' instead of 'make' on macOS.)
+endif
+
+TARGETS = apple2 apple2enh atari c64 coco
 PROGRAM := fujinet.lib
 
 SUB_TASKS := clean disk test release unit-test
diff --git a/apple2/apple2-6502/bus/sp_init.s b/apple2/apple2-6502/bus/sp_init.s
index 2de95db..3393e9b 100644
--- a/apple2/apple2-6502/bus/sp_init.s
+++ b/apple2/apple2-6502/bus/sp_init.s
@@ -10,7 +10,7 @@
 
         .include        "macros.inc"
         .include        "zp.inc"
-        .macpack        cpu
+        .include        "cpu.inc"
 
 ; Find the SmartPort device that has a FujiNet NETWORK adapter on it.
 ; Really we should search for the FUJI device on it, but historically that was
diff --git a/common/inc/cpu.inc b/common/inc/cpu.inc
new file mode 100644
index 0000000..264b73b
--- /dev/null
+++ b/common/inc/cpu.inc
@@ -0,0 +1,7 @@
+; Guard to prevent multiple inclusion of cpu macros
+; Check if CPU_ISET_NONE is already defined (from cpu.mac)
+.ifndef CPU_ISET_NONE
+
+.macpack cpu
+
+.endif
diff --git a/fujinet-fuji.h b/fujinet-fuji.h
index bbff5c7..bad2014 100644
--- a/fujinet-fuji.h
+++ b/fujinet-fuji.h
@@ -6,20 +6,25 @@
 // In general, bools return the "success" status, so true is good, false is bad.
 
 #ifdef _CMOC_VERSION_
-    #include <cmoc.h>
-    #include <coco.h>
-
-    #ifndef bool
-    #define bool _FNBool
-    typedef unsigned char _FNBool;
-    #endif /* bool */
-
-    #define true  1
-    #define false 0
+// CMOC-specific types and definitions
+#ifndef bool
+#define bool unsigned char
+#endif /* bool */
+
+#define true  1
+#define false 0
+
+// Define standard integer types for CMOC
+#define uint8_t unsigned char
+#define int8_t signed char
+#define uint16_t unsigned short
+#define int16_t signed short
+#define uint32_t unsigned long
+#define int32_t signed long
 #else
-    #include <stddef.h>
-    #include <stdbool.h>
-    #include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <stdint.h>
 #endif /* _CMOC_VERSION_ */
 
 #ifdef __CBM__
diff --git a/makefiles/compiler-cmoc.mk b/makefiles/compiler-cmoc.mk
index 21a6544..135cbb0 100644
--- a/makefiles/compiler-cmoc.mk
+++ b/makefiles/compiler-cmoc.mk
@@ -1,6 +1,6 @@
 CC        := cmoc
 AR        := lwar
-CFLAGS    := -O2
+CFLAGS    := -O2 -D_CMOC_VERSION_=1
 
 INCC_ARG  := -I
 INCS_ARG  := -I