diff --git a/Makefile b/Makefile
index 25dd7a8..8e09083 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 CC=gcc
-CFLAGS=-Wall -pedantic -g -DNO_DEBUGGER -DUNIX_HOST -DVER=\"`git show-ref --abbrev=8 --head --hash head`\" -DTAG=\"`git describe --abbrev=0 --tags`\"
+CFLAGS=-Wall -pedantic -g -DDEBUGGER -DUNIX_HOST -DVER=\"`git show-ref --abbrev=8 --head --hash head`\" -DTAG=\"`git describe --abbrev=0 --tags`\"
 LIBS=-lm -lreadline
 
 TARGET	= picoc
diff --git a/debug.c b/debug.c
index b76bf5f..cd437a3 100644
--- a/debug.c
+++ b/debug.c
@@ -1,6 +1,6 @@
 /* picoc interactive debugger */
 
-#ifndef NO_DEBUGGER
+#ifdef DEBUGGER
 
 #include "interpreter.h"
 
@@ -115,4 +115,4 @@ void DebugCheckStatement(struct ParseState *Parser)
 void DebugStep()
 {
 }
-#endif /* !NO_DEBUGGER */
+#endif /* DEBUGGER */
diff --git a/interpreter.h b/interpreter.h
index f5498f0..2dc9dae 100644
--- a/interpreter.h
+++ b/interpreter.h
@@ -586,10 +586,10 @@ extern void IncludeFile(Picoc *pc, char *Filename);
 /* the following is defined in picoc.h:
  * void PicocIncludeAllSystemHeaders(); */
 
-#ifndef NO_DEBUGGER
+#ifdef DEBUGGER
 /* debug.c */
-extern void DebugInit();
-extern void DebugCleanup();
+extern void DebugInit(Picoc *pc);
+extern void DebugCleanup(Picoc *pc);
 extern void DebugCheckStatement(struct ParseState *Parser);
 #endif
 
diff --git a/parse.c b/parse.c
index bd19e41..185a533 100644
--- a/parse.c
+++ b/parse.c
@@ -528,7 +528,7 @@ enum ParseResult ParseStatement(struct ParseState *Parser, int CheckTrailingSemi
 
     /* if we're debugging, check for a breakpoint */
     if (Parser->DebugMode && Parser->Mode == RunModeRun)
-#ifndef NO_DEBUGGER
+#ifdef DEBUGGER
         DebugCheckStatement(Parser)
 #endif
         ;
diff --git a/platform.c b/platform.c
index d0d90b2..1b198f7 100644
--- a/platform.c
+++ b/platform.c
@@ -4,10 +4,10 @@
 #include "picoc.h"
 #include "interpreter.h"
 
-#ifdef NO_DEBUGGER
-static int gEnableDebugger = FALSE;
-#else
+#ifdef DEBUGGER
 static int gEnableDebugger = TRUE;
+#else
+static int gEnableDebugger = FALSE;
 #endif
 
 
@@ -25,7 +25,7 @@ void PicocInitialise(Picoc *pc, int StackSize)
     IncludeInit(pc);
     LibraryInit(pc);
     PlatformLibraryInit(pc);
-#ifndef NO_DEBUGGER
+#ifdef DEBUGGER
     DebugInit(pc);
 #endif
 }
@@ -33,7 +33,7 @@ void PicocInitialise(Picoc *pc, int StackSize)
 /* free memory */
 void PicocCleanup(Picoc *pc)
 {
-#ifndef NO_DEBUGGER
+#ifdef DEBUGGER
     DebugCleanup(pc);
 #endif
     IncludeCleanup(pc);
diff --git a/platform/platform_msvc.c b/platform/platform_msvc.c
index 582df64..4bc3e9e 100644
--- a/platform/platform_msvc.c
+++ b/platform/platform_msvc.c
@@ -1,10 +1,10 @@
 #include "../picoc.h"
 #include "../interpreter.h"
 
-#ifdef NO_DEBUGGER
-static int gEnableDebugger = FALSE;
-#else
+#ifdef DEBUGGER
 static int gEnableDebugger = TRUE;
+#else
+static int gEnableDebugger = FALSE;
 #endif
 
 /* mark where to end the program for platforms which require this */
diff --git a/platform/platform_unix.c b/platform/platform_unix.c
index 9efe780..fb47d97 100644
--- a/platform/platform_unix.c
+++ b/platform/platform_unix.c
@@ -6,16 +6,16 @@
 #include <readline/history.h>
 #endif
 
-#ifdef NO_DEBUGGER
-static int gEnableDebugger = FALSE;
-#else
+#ifdef DEBUGGER
 static int gEnableDebugger = TRUE;
+#else
+static int gEnableDebugger = FALSE;
 #endif
 
 /* mark where to end the program for platforms which require this */
 jmp_buf PicocExitBuf;
 
-#ifndef NO_DEBUGGER
+#ifdef DEBUGGER
 #include <signal.h>
 
 Picoc *break_pc = NULL;
@@ -32,14 +32,10 @@ void PlatformInit(Picoc *pc)
     signal(SIGINT, BreakHandler);
 }
 #else
-void PlatformInit(Picoc *pc)
-{
-}
+void PlatformInit(Picoc *pc) { }
 #endif
 
-void PlatformCleanup(Picoc *pc)
-{
-}
+void PlatformCleanup(Picoc *pc) { }
 
 /* get a line of interactive input */
 char *PlatformGetLine(char *Buf, int MaxLen, const char *Prompt)