diff --git a/defs.h b/defs.h
index 4a8351fe..27062774 100644
--- a/defs.h
+++ b/defs.h
@@ -11,6 +11,13 @@
 #ifndef PUTTY_DEFS_H
 #define PUTTY_DEFS_H
 
+#ifndef FALSE
+#define FALSE 0
+#endif
+#ifndef TRUE
+#define TRUE 1
+#endif
+
 typedef struct conf_tag Conf;
 typedef struct backend_tag Backend;
 typedef struct terminal_tag Terminal;
diff --git a/misc.h b/misc.h
index 271d34f1..c4da3d6d 100644
--- a/misc.h
+++ b/misc.h
@@ -13,13 +13,6 @@
 #include <stdarg.h>		       /* for va_list */
 #include <time.h>                      /* for struct tm */
 
-#ifndef FALSE
-#define FALSE 0
-#endif
-#ifndef TRUE
-#define TRUE 1
-#endif
-
 unsigned long parse_blocksize(const char *bs);
 char ctrlparse(char *s, char **next);
 
diff --git a/portfwd.c b/portfwd.c
index 2512415c..f2652557 100644
--- a/portfwd.c
+++ b/portfwd.c
@@ -8,13 +8,6 @@
 #include "putty.h"
 #include "ssh.h"
 
-#ifndef FALSE
-#define FALSE 0
-#endif
-#ifndef TRUE
-#define TRUE 1
-#endif
-
 struct PortForwarding {
     const struct plug_function_table *fn;
     /* the above variable absolutely *must* be the first in this structure */
diff --git a/raw.c b/raw.c
index fbc9018d..d0840a1a 100644
--- a/raw.c
+++ b/raw.c
@@ -8,13 +8,6 @@
 
 #include "putty.h"
 
-#ifndef FALSE
-#define FALSE 0
-#endif
-#ifndef TRUE
-#define TRUE 1
-#endif
-
 #define RAW_MAX_BACKLOG 4096
 
 typedef struct raw_backend_data {
diff --git a/rlogin.c b/rlogin.c
index cd6260d2..ccb75119 100644
--- a/rlogin.c
+++ b/rlogin.c
@@ -9,13 +9,6 @@
 
 #include "putty.h"
 
-#ifndef FALSE
-#define FALSE 0
-#endif
-#ifndef TRUE
-#define TRUE 1
-#endif
-
 #define RLOGIN_MAX_BACKLOG 4096
 
 typedef struct rlogin_tag {
diff --git a/ssh.c b/ssh.c
index b4482753..f220d5df 100644
--- a/ssh.c
+++ b/ssh.c
@@ -25,13 +25,6 @@
 #define GSS_CTXT_MAYFAIL (1<<3)	/* Context may expire during handshake */
 #endif
 
-#ifndef FALSE
-#define FALSE 0
-#endif
-#ifndef TRUE
-#define TRUE 1
-#endif
-
 /*
  * Packet type contexts, so that ssh2_pkt_type can correctly decode
  * the ambiguous type numbers back into the correct type strings.
diff --git a/sshzlib.c b/sshzlib.c
index 60447fdf..855ddd86 100644
--- a/sshzlib.c
+++ b/sshzlib.c
@@ -41,6 +41,8 @@
 #include <string.h>
 #include <assert.h>
 
+#include "defs.h"
+
 #ifdef ZLIB_STANDALONE
 
 /*
@@ -57,13 +59,15 @@
 #define sresize(x, n, type) ( (type *) realloc((x), (n) * sizeof(type)) )
 #define sfree(x) ( free((x)) )
 
-#else
-#include "ssh.h"
-#endif
-
 #ifndef FALSE
 #define FALSE 0
-#define TRUE (!FALSE)
+#endif
+#ifndef TRUE
+#define TRUE 1
+#endif
+
+#else
+#include "ssh.h"
 #endif
 
 /* ----------------------------------------------------------------------
diff --git a/telnet.c b/telnet.c
index 8d03cb7b..0857113c 100644
--- a/telnet.c
+++ b/telnet.c
@@ -8,13 +8,6 @@
 
 #include "putty.h"
 
-#ifndef FALSE
-#define FALSE 0
-#endif
-#ifndef TRUE
-#define TRUE 1
-#endif
-
 #define	IAC	255		       /* interpret as command: */
 #define	DONT	254		       /* you are not to use option */
 #define	DO	253		       /* please, you use option */
diff --git a/unix/uxpty.c b/unix/uxpty.c
index a6069ce6..7aaad8ac 100644
--- a/unix/uxpty.c
+++ b/unix/uxpty.c
@@ -29,13 +29,6 @@
 #include <utmpx.h>
 #endif
 
-#ifndef FALSE
-#define FALSE 0
-#endif
-#ifndef TRUE
-#define TRUE 1
-#endif
-
 /* updwtmpx() needs the name of the wtmp file.  Try to find it. */
 #ifndef WTMPX_FILE
 #ifdef _PATH_WTMPX