diff --git a/cfg/module.cfg b/cfg/module.cfg
index edc87fb17..349197eb0 100644
--- a/cfg/module.cfg
+++ b/cfg/module.cfg
@@ -10,7 +10,7 @@ SEGMENTS {
     DATA:      load = COMBINED, type = rw,  define = yes;
     BSS:       load = COMBINED, type = bss, define = yes;
     ZEROPAGE:  load = ZP,       type = zp;
-    EXTZP:     load = ZP,       type = zp;
+    EXTZP:     load = ZP,       type = zp,  optional = yes;
 }
 FILES {
     %O: format = o65;
diff --git a/include/cbm264.h b/include/cbm264.h
index 9ede10f47..ff7468d30 100644
--- a/include/cbm264.h
+++ b/include/cbm264.h
@@ -39,7 +39,7 @@
 
 
 /* Check for errors */
-#if !defined(__PLUS4__) && !defined(__C16__)
+#if !defined(__C16__)
 #  error This module may only be used when compiling for the Plus/4 or C16!
 #endif
 
diff --git a/libsrc/dbg/dbg.c b/libsrc/dbg/dbg.c
index c0c2da971..00ff28722 100644
--- a/libsrc/dbg/dbg.c
+++ b/libsrc/dbg/dbg.c
@@ -47,7 +47,7 @@ static char GetKeyUpdate (void);
 
 
 /* Color definitions */
-#if defined(__PLUS4__) || defined(__C16__)
+#if defined(__C16__)
 #  define COLOR_BORDER          (BCOLOR_DARKBLUE | CATTR_LUMA6)
 #  define COLOR_BACKGROUND      COLOR_WHITE
 #  define COLOR_TEXTHIGH        COLOR_BLACK
diff --git a/libsrc/runtime/zeropage.s b/libsrc/runtime/zeropage.s
index b4af44e33..2bbe7ceee 100644
--- a/libsrc/runtime/zeropage.s
+++ b/libsrc/runtime/zeropage.s
@@ -22,10 +22,3 @@ tmp2:           .res    1
 tmp3:           .res    1
 tmp4:           .res    1
 regbank:        .res    regbanksize     ; Register bank
-
-; Add an empty EXTZP zeropage segment to avoid linker warnings that this
-; segment does not exist (it does not exist in most builtin linker configs
-; but is used when linking modules).
-
-.segment        "EXTZP" : zeropage
-
diff --git a/libsrc/sim6502/exehdr.s b/libsrc/sim6502/exehdr.s
index 9c895834c..865bd6553 100644
--- a/libsrc/sim6502/exehdr.s
+++ b/libsrc/sim6502/exehdr.s
@@ -6,8 +6,6 @@
 
         .export         __EXEHDR__ : absolute = 1       ; Linker referenced
 
-; ------------------------------------------------------------------------
-
         .segment        "EXEHDR"
 
         .byte   .defined(__SIM65C02__)
diff --git a/src/ca65/main.c b/src/ca65/main.c
index c862dcaad..4b2f9d178 100644
--- a/src/ca65/main.c
+++ b/src/ca65/main.c
@@ -230,7 +230,8 @@ static void SetSys (const char* Sys)
             break;
 
         case TGT_PLUS4:
-            CBMSystem ("__PLUS4__");
+            CBMSystem ("__C16__");
+            NewSymbol ("__PLUS4__", 1);
             break;
 
         case TGT_CBM510:
diff --git a/src/cc65/main.c b/src/cc65/main.c
index cadad83d0..a27822ed8 100644
--- a/src/cc65/main.c
+++ b/src/cc65/main.c
@@ -186,7 +186,8 @@ static void SetSys (const char* Sys)
             break;
 
         case TGT_PLUS4:
-            cbmsys ("__PLUS4__");
+            cbmsys ("__C16__");
+            DefineNumericMacro ("__PLUS4__", 1);
             break;
 
         case TGT_CBM510: