diff --git a/pg_ivm.c b/pg_ivm.c
index 32641dd..569e920 100644
--- a/pg_ivm.c
+++ b/pg_ivm.c
@@ -191,6 +191,8 @@ create_immv(PG_FUNCTION_ARGS)
 	CreateTableAsStmt *ctas;
 	StringInfoData command_buf;
 
+	warnIfPgIvmNotPreloaded();
+
 	parseNameAndColumns(relname, &names, &colNames);
 
 	initStringInfo(&command_buf);
@@ -250,6 +252,8 @@ refresh_immv(PG_FUNCTION_ARGS)
 	QueryCompletion qc;
 	StringInfoData command_buf;
 
+	warnIfPgIvmNotPreloaded();
+
 	initStringInfo(&command_buf);
 	appendStringInfo(&command_buf, "SELECT refresh_immv('%s, %s);",
 					 relname, ispopulated ? "true" : "false");
@@ -364,6 +368,8 @@ get_immv_def(PG_FUNCTION_ARGS)
 	Query *query = NULL;
 	char *querystring = NULL;
 
+	warnIfPgIvmNotPreloaded();
+
 	/* Make sure IMMV is a table. */
 	if (get_rel_relkind(matviewOid) != RELKIND_RELATION)
 		PG_RETURN_NULL();