diff --git a/doc/src/sgml/ref/alter_function.sgml b/doc/src/sgml/ref/alter_function.sgml
index 013b6f8..cfc2a69 100644
*** a/doc/src/sgml/ref/alter_function.sgml
--- b/doc/src/sgml/ref/alter_function.sgml
***************
*** 54,59 **** ALTER FUNCTION <replaceable>name</replaceable> ( [ [ <replaceable class="paramet
--- 54,61 ----
  
    <para>
     You must own the function to use <command>ALTER FUNCTION</>.
+    Marking a function <literal>CALLED ON NULL INPUT</> also requires
+    permission to use the function's language when creating new functions.
     To change a function's schema, you must also have <literal>CREATE</>
     privilege on the new schema.
     To alter the owner, you must also be a direct or indirect member of the new
diff --git a/src/backend/commands/functioncindex 13e30f4..b40bcdf 100644
*** a/src/backend/commands/functioncmds.c
--- b/src/backend/commands/functioncmds.c
***************
*** 70,75 **** static void AlterFunctionOwner_internal(Relation rel, HeapTuple tup,
--- 70,107 ----
  
  
  /*
+  * May the current user create functions of a given language?
+  */
+ static void
+ check_language_usage(HeapTuple languageTuple)
+ {
+ 	Oid			languageOid;
+ 	Form_pg_language languageStruct;
+ 
+ 	languageOid = HeapTupleGetOid(languageTuple);
+ 	languageStruct = (Form_pg_language) GETSTRUCT(languageTuple);
+ 
+ 	if (languageStruct->lanpltrusted)
+ 	{
+ 		/* if trusted language, need USAGE privilege */
+ 		AclResult	aclresult;
+ 
+ 		aclresult = pg_language_aclcheck(languageOid, GetUserId(), ACL_USAGE);
+ 		if (aclresult != ACLCHECK_OK)
+ 			aclcheck_error(aclresult, ACL_KIND_LANGUAGE,
+ 						   NameStr(languageStruct->lanname));
+ 	}
+ 	else
+ 	{
+ 		/* if untrusted language, must be superuser */
+ 		if (!superuser())
+ 			aclcheck_error(ACLCHECK_NO_PRIV, ACL_KIND_LANGUAGE,
+ 						   NameStr(languageStruct->lanname));
+ 	}
+ }
+ 
+ 
+ /*
   *	 Examine the RETURNS clause of the CREATE FUNCTION statement
   *	 and return information about it as *prorettype_p and *returnsSet.
   *
***************
*** 864,890 **** CreateFunction(CreateFunctionStmt *stmt, const char *queryString)
  				 (PLTemplateExists(language) ?
  				  errhint("Use CREATE LANGUAGE to load the language into the database.") : 0)));
  
  	languageOid = HeapTupleGetOid(languageTuple);
  	languageStruct = (Form_pg_language) GETSTRUCT(languageTuple);
- 
- 	if (languageStruct->lanpltrusted)
- 	{
- 		/* if trusted language, need USAGE privilege */
- 		AclResult	aclresult;
- 
- 		aclresult = pg_language_aclcheck(languageOid, GetUserId(), ACL_USAGE);
- 		if (aclresult != ACLCHECK_OK)
- 			aclcheck_error(aclresult, ACL_KIND_LANGUAGE,
- 						   NameStr(languageStruct->lanname));
- 	}
- 	else
- 	{
- 		/* if untrusted language, must be superuser */
- 		if (!superuser())
- 			aclcheck_error(ACLCHECK_NO_PRIV, ACL_KIND_LANGUAGE,
- 						   NameStr(languageStruct->lanname));
- 	}
- 
  	languageValidator = languageStruct->lanvalidator;
  
  	ReleaseSysCache(languageTuple);
--- 896,905 ----
  				 (PLTemplateExists(language) ?
  				  errhint("Use CREATE LANGUAGE to load the language into the database.") : 0)));
  
+ 	check_language_usage(languageTuple);
+ 
  	languageOid = HeapTupleGetOid(languageTuple);
  	languageStruct = (Form_pg_language) GETSTRUCT(languageTuple);
  	languageValidator = languageStruct->lanvalidator;
  
  	ReleaseSysCache(languageTuple);
***************
*** 1312,1318 **** AlterFunction(AlterFunctionStmt *stmt)
--- 1327,1355 ----
  	if (volatility_item)
  		procForm->provolatile = interpret_func_volatility(volatility_item);
  	if (strict_item)
+ 	{
+ 		/*
+ 		 * C-language functions that expect to be declared STRICT often omit
+ 		 * NULL argument checks, crashing if they do receive a NULL.  To
+ 		 * protect such functions against less-privileged owners, clearing
+ 		 * proisstrict requires the authority to define a new function of the
+ 		 * same language.
+ 		 */
+ 		if (!intVal(strict_item->arg))
+ 		{
+ 			HeapTuple	langTuple;
+ 
+ 			langTuple = SearchSysCache1(LANGOID,
+ 										PointerGetDatum(procForm->prolang));
+ 			if (!HeapTupleIsValid(langTuple))
+ 				elog(ERROR, "cache lookup failed for language %u",
+ 					 procForm->prolang);
+ 			check_language_usage(langTuple);
+ 			ReleaseSysCache(langTuple);
+ 		}
+ 
  		procForm->proisstrict = intVal(strict_item->arg);
+ 	}
  	if (security_def_item)
  		procForm->prosecdef = intVal(security_def_item->arg);
  	if (leakproof_item)
***************
*** 1974,2002 **** ExecuteDoStmt(DoStmt *stmt)
  				 (PLTemplateExists(language) ?
  				  errhint("Use CREATE LANGUAGE to load the language into the database.") : 0)));
  
  	codeblock->langOid = HeapTupleGetOid(languageTuple);
  	languageStruct = (Form_pg_language) GETSTRUCT(languageTuple);
  	codeblock->langIsTrusted = languageStruct->lanpltrusted;
  
- 	if (languageStruct->lanpltrusted)
- 	{
- 		/* if trusted language, need USAGE privilege */
- 		AclResult	aclresult;
- 
- 		aclresult = pg_language_aclcheck(codeblock->langOid, GetUserId(),
- 										 ACL_USAGE);
- 		if (aclresult != ACLCHECK_OK)
- 			aclcheck_error(aclresult, ACL_KIND_LANGUAGE,
- 						   NameStr(languageStruct->lanname));
- 	}
- 	else
- 	{
- 		/* if untrusted language, must be superuser */
- 		if (!superuser())
- 			aclcheck_error(ACLCHECK_NO_PRIV, ACL_KIND_LANGUAGE,
- 						   NameStr(languageStruct->lanname));
- 	}
- 
  	/* get the handler function's OID */
  	laninline = languageStruct->laninline;
  	if (!OidIsValid(laninline))
--- 2011,2022 ----
  				 (PLTemplateExists(language) ?
  				  errhint("Use CREATE LANGUAGE to load the language into the database.") : 0)));
  
+ 	check_language_usage(languageTuple);
+ 
  	codeblock->langOid = HeapTupleGetOid(languageTuple);
  	languageStruct = (Form_pg_language) GETSTRUCT(languageTuple);
  	codeblock->langIsTrusted = languageStruct->lanpltrusted;
  
  	/* get the handler function's OID */
  	laninline = languageStruct->laninline;
  	if (!OidIsValid(laninline))