diff --git a/plr.c b/plr.c
index 68170299..c224e8f1 100755
--- a/plr.c
+++ b/plr.c
@@ -729,16 +729,9 @@ compile_plr_function(FunctionCallInfo fcinfo)
 
 	if (function)
 	{
-		bool	function_valid;
-
 		/* We have a compiled function, but is it still valid? */
-		if (function->fn_xmin == HeapTupleHeaderGetXmin(procTup->t_data) &&
-			ItemPointerEquals(&function->fn_tid, &procTup->t_self))
-			function_valid = true;
-		else
-			function_valid = false;
-
-		if (!function_valid)
+		if (!(function->fn_xmin == HeapTupleHeaderGetXmin(procTup->t_data) &&
+			  function->fn_cmin == HeapTupleHeaderGetCmin(procTup->t_data)))
 		{
 			/*
 			 * Nope, drop the hashtable entry.  XXX someday, free all the
@@ -843,7 +836,7 @@ do_compile(FunctionCallInfo fcinfo,
 
 	function->proname = pstrdup(proname);
 	function->fn_xmin = HeapTupleHeaderGetXmin(procTup->t_data);
-	function->fn_tid = procTup->t_self;
+	function->fn_cmin = HeapTupleHeaderGetCmin(procTup->t_data);
 
 	/* Lookup the pg_language tuple by Oid*/
 	langTup = SearchSysCache(LANGOID,
diff --git a/plr.h b/plr.h
index 1eefeb8d..2b71f2d8 100755
--- a/plr.h
+++ b/plr.h
@@ -82,11 +82,11 @@
 
 /* working with postgres 7.3 compatible sources */
 #if (CATALOG_VERSION_NO <= 200510211)
-#error "This version of PL/R only builds with PostgreSQL 8.2 or later"
+#error "This version of PL/R only builds with PostgreSQL 8.2"
 #elif (CATALOG_VERSION_NO <= 200611241)
 #define PG_VERSION_82_COMPAT
 #else
-#define PG_VERSION_83_COMPAT
+#error "This version of PL/R only builds with PostgreSQL 8.2"
 #endif
 
 #ifdef DEBUGPROTECT
@@ -389,7 +389,7 @@ typedef struct plr_function
 {
 	char			   *proname;
 	TransactionId		fn_xmin;
-	ItemPointerData		fn_tid;
+	CommandId			fn_cmin;
 	plr_func_hashkey   *fn_hashkey; /* back-link to hashtable key */
 	bool				lanpltrusted;
 	Oid					result_typid;