diff --git a/src/mzscheme/include/mzscheme.exp b/src/mzscheme/include/mzscheme.exp
index 2c28fd9017..ac24cae8e5 100644
--- a/src/mzscheme/include/mzscheme.exp
+++ b/src/mzscheme/include/mzscheme.exp
@@ -457,6 +457,7 @@ scheme_fdclr
 scheme_fdisset
 scheme_add_fd_handle
 scheme_add_fd_eventmask
+scheme_collapse_win_fd
 scheme_security_check_file
 scheme_security_check_file_link
 scheme_security_check_network
diff --git a/src/mzscheme/include/mzscheme3m.exp b/src/mzscheme/include/mzscheme3m.exp
index 23666cd019..ac6876fdc3 100644
--- a/src/mzscheme/include/mzscheme3m.exp
+++ b/src/mzscheme/include/mzscheme3m.exp
@@ -468,6 +468,7 @@ scheme_fdclr
 scheme_fdisset
 scheme_add_fd_handle
 scheme_add_fd_eventmask
+scheme_collapse_win_fd
 scheme_security_check_file
 scheme_security_check_file_link
 scheme_security_check_network
diff --git a/src/mzscheme/include/mzwin.def b/src/mzscheme/include/mzwin.def
index 55296444a6..e52df5313c 100644
--- a/src/mzscheme/include/mzwin.def
+++ b/src/mzscheme/include/mzwin.def
@@ -445,6 +445,7 @@ EXPORTS
  scheme_fdisset
  scheme_add_fd_handle
  scheme_add_fd_eventmask
+ scheme_collapse_win_fd
  scheme_security_check_file
  scheme_security_check_file_link
  scheme_security_check_network
diff --git a/src/mzscheme/include/mzwin3m.def b/src/mzscheme/include/mzwin3m.def
index c3f9ee33a4..9e2f1bd4ef 100644
--- a/src/mzscheme/include/mzwin3m.def
+++ b/src/mzscheme/include/mzwin3m.def
@@ -460,6 +460,7 @@ EXPORTS
  scheme_fdisset
  scheme_add_fd_handle
  scheme_add_fd_eventmask
+ scheme_collapse_win_fd
  scheme_security_check_file
  scheme_security_check_file_link
  scheme_security_check_network
diff --git a/src/mzscheme/src/port.c b/src/mzscheme/src/port.c
index 74c7114bd3..f10ffc67a6 100644
--- a/src/mzscheme/src/port.c
+++ b/src/mzscheme/src/port.c
@@ -868,6 +868,10 @@ void scheme_add_fd_eventmask(void *fds, int mask)
 #endif
 }
 
+void scheme_collapse_win_fd(void *fds)
+{
+}
+
 /*========================================================================*/
 /*                      Windows thread suspension                         */
 /*========================================================================*/
diff --git a/src/mzscheme/src/schemef.h b/src/mzscheme/src/schemef.h
index baa6514acd..0a52678a7e 100644
--- a/src/mzscheme/src/schemef.h
+++ b/src/mzscheme/src/schemef.h
@@ -875,6 +875,7 @@ MZ_EXTERN void scheme_fdclr(void *fd, int pos);
 MZ_EXTERN int scheme_fdisset(void *fd, int pos);
 MZ_EXTERN void scheme_add_fd_handle(void *h, void *fds, int repost);
 MZ_EXTERN void scheme_add_fd_eventmask(void *fds, int mask);
+MZ_EXTERN void scheme_collapse_win_fd(void *fds);
 
 MZ_EXTERN void scheme_security_check_file(const char *who, const char *filename, int guards);
 MZ_EXTERN void scheme_security_check_file_link(const char *who, const char *filename, const char *content);
diff --git a/src/mzscheme/src/schemex.h b/src/mzscheme/src/schemex.h
index a6e4966bbe..6a3224ac99 100644
--- a/src/mzscheme/src/schemex.h
+++ b/src/mzscheme/src/schemex.h
@@ -735,6 +735,7 @@ void (*scheme_fdclr)(void *fd, int pos);
 int (*scheme_fdisset)(void *fd, int pos);
 void (*scheme_add_fd_handle)(void *h, void *fds, int repost);
 void (*scheme_add_fd_eventmask)(void *fds, int mask);
+void (*scheme_collapse_win_fd)(void *fds);
 void (*scheme_security_check_file)(const char *who, const char *filename, int guards);
 void (*scheme_security_check_file_link)(const char *who, const char *filename, const char *content);
 void (*scheme_security_check_network)(const char *who, const char *host, int port, int client);
diff --git a/src/mzscheme/src/schemex.inc b/src/mzscheme/src/schemex.inc
index e18aeab800..0753e7a6eb 100644
--- a/src/mzscheme/src/schemex.inc
+++ b/src/mzscheme/src/schemex.inc
@@ -512,6 +512,7 @@
   scheme_extension_table->scheme_fdisset = scheme_fdisset;
   scheme_extension_table->scheme_add_fd_handle = scheme_add_fd_handle;
   scheme_extension_table->scheme_add_fd_eventmask = scheme_add_fd_eventmask;
+  scheme_extension_table->scheme_collapse_win_fd = scheme_collapse_win_fd;
   scheme_extension_table->scheme_security_check_file = scheme_security_check_file;
   scheme_extension_table->scheme_security_check_file_link = scheme_security_check_file_link;
   scheme_extension_table->scheme_security_check_network = scheme_security_check_network;
diff --git a/src/mzscheme/src/schemexm.h b/src/mzscheme/src/schemexm.h
index 20b0998e6c..fec4281b78 100644
--- a/src/mzscheme/src/schemexm.h
+++ b/src/mzscheme/src/schemexm.h
@@ -512,6 +512,7 @@
 #define scheme_fdisset (scheme_extension_table->scheme_fdisset)
 #define scheme_add_fd_handle (scheme_extension_table->scheme_add_fd_handle)
 #define scheme_add_fd_eventmask (scheme_extension_table->scheme_add_fd_eventmask)
+#define scheme_collapse_win_fd (scheme_extension_table->scheme_collapse_win_fd)
 #define scheme_security_check_file (scheme_extension_table->scheme_security_check_file)
 #define scheme_security_check_file_link (scheme_extension_table->scheme_security_check_file_link)
 #define scheme_security_check_network (scheme_extension_table->scheme_security_check_network)