diff --git a/os/osdep.h b/os/osdep.h
index b0d30e9ee..3d75bbaab 100644
--- a/os/osdep.h
+++ b/os/osdep.h
@@ -56,7 +56,9 @@ SOFTWARE.
 #define BUFSIZE 4096
 #define BUFWATERMARK 8192
 
+#if defined(XDMCP) || defined(HASXDMAUTH)
 #include <X11/Xdmcp.h>
+#endif
 
 #ifdef _POSIX_SOURCE
 #include <limits.h>
@@ -109,9 +111,11 @@ SOFTWARE.
 
 #include <stddef.h>
 
+#if defined(XDMCP) || defined(HASXDMAUTH)
 typedef Bool (*ValidatorFunc)(ARRAY8Ptr Auth, ARRAY8Ptr Data, int packet_type);
 typedef Bool (*GeneratorFunc)(ARRAY8Ptr Auth, ARRAY8Ptr Data, int packet_type);
 typedef Bool (*AddAuthorFunc)(unsigned name_length, char *name, unsigned data_length, char *data);
+#endif
 
 typedef struct _connectionInput {
     struct _connectionInput *next;
@@ -244,6 +248,7 @@ extern int  SecureRPCRemove   (AuthRemCArgs);
 extern int  SecureRPCReset    (AuthRstCArgs);
 #endif
 
+#ifdef XDMCP
 /* in xdmcp.c */
 extern void XdmcpUseMsg (void);
 extern int XdmcpOptions(int argc, char **argv, int i);
@@ -268,6 +273,7 @@ extern void XdmcpRegisterAuthentication (
 
 struct sockaddr_in;
 extern void XdmcpRegisterBroadcastAddress (struct sockaddr_in *addr);
+#endif
 
 #ifdef HASXDMAUTH
 extern void XdmAuthenticationInit (char *cookie, int cookie_length);