diff -r 642247a536d5 Modules/clinic/zlibmodule.c.h
--- a/Modules/clinic/zlibmodule.c.h	Sat Mar 14 20:17:38 2015 -0700
+++ b/Modules/clinic/zlibmodule.c.h	Sat Mar 14 21:24:32 2015 -0700
@@ -340,10 +340,6 @@
 
 #endif /* defined(HAVE_ZLIB_COPY) */
 
-#ifndef ZLIB_DECOMPRESS_COPY_METHODDEF
-    #define ZLIB_DECOMPRESS_COPY_METHODDEF
-#endif /* !defined(ZLIB_DECOMPRESS_COPY_METHODDEF) */
-
 PyDoc_STRVAR(zlib_Decompress_flush__doc__,
 "flush($self, length=zlib.DEF_BUF_SIZE, /)\n"
 "--\n"
@@ -450,4 +446,4 @@
 
     return return_value;
 }
-/*[clinic end generated code: output=bc9473721ca7c962 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=a5043cb42760f0ee input=a9049054013a1b77]*/
diff -r 642247a536d5 Modules/posixmodule.c
--- a/Modules/posixmodule.c	Sat Mar 14 20:17:38 2015 -0700
+++ b/Modules/posixmodule.c	Sat Mar 14 21:24:32 2015 -0700
@@ -17212,10 +17212,6 @@
     #define OS_SYSTEM_METHODDEF
 #endif /* !defined(OS_SYSTEM_METHODDEF) */
 
-#ifndef OS_SYSTEM_METHODDEF
-    #define OS_SYSTEM_METHODDEF
-#endif /* !defined(OS_SYSTEM_METHODDEF) */
-
 #ifndef OS_UNAME_METHODDEF
     #define OS_UNAME_METHODDEF
 #endif /* !defined(OS_UNAME_METHODDEF) */
@@ -17388,10 +17384,6 @@
     #define OS_WAITPID_METHODDEF
 #endif /* !defined(OS_WAITPID_METHODDEF) */
 
-#ifndef OS_WAITPID_METHODDEF
-    #define OS_WAITPID_METHODDEF
-#endif /* !defined(OS_WAITPID_METHODDEF) */
-
 #ifndef OS_WAIT_METHODDEF
     #define OS_WAIT_METHODDEF
 #endif /* !defined(OS_WAIT_METHODDEF) */
@@ -17492,10 +17484,6 @@
     #define OS_PUTENV_METHODDEF
 #endif /* !defined(OS_PUTENV_METHODDEF) */
 
-#ifndef OS_PUTENV_METHODDEF
-    #define OS_PUTENV_METHODDEF
-#endif /* !defined(OS_PUTENV_METHODDEF) */
-
 #ifndef OS_UNSETENV_METHODDEF
     #define OS_UNSETENV_METHODDEF
 #endif /* !defined(OS_UNSETENV_METHODDEF) */
@@ -17603,7 +17591,7 @@
 #ifndef OS_SET_HANDLE_INHERITABLE_METHODDEF
     #define OS_SET_HANDLE_INHERITABLE_METHODDEF
 #endif /* !defined(OS_SET_HANDLE_INHERITABLE_METHODDEF) */
-/*[clinic end generated code: output=52a6140b0b052ce6 input=524ce2e021e4eba6]*/
+/*[clinic end generated code: output=b788c2d6010113e8 input=524ce2e021e4eba6]*/
 
 
 static PyMethodDef posix_methods[] = {
diff -r 642247a536d5 Tools/clinic/clinic.py
--- a/Tools/clinic/clinic.py	Sat Mar 14 20:17:38 2015 -0700
+++ b/Tools/clinic/clinic.py	Sat Mar 14 21:24:32 2015 -0700
@@ -820,7 +820,8 @@
             cpp_if = "#if " + conditional
             cpp_endif = "#endif /* " + conditional + " */"
 
-            if methoddef_define:
+            if methoddef_define and f.name not in clinic.ifndef_symbols:
+                clinic.ifndef_symbols.add(f.name)
                 methoddef_ifndef = normalize_snippet("""
                     #ifndef {methoddef_name}
                         #define {methoddef_name}
@@ -1574,6 +1575,7 @@
         ))
 
         self.field_destinations_stack = []
+        self.ifndef_symbols = set()
 
         self.presets = {}
         preset = None