Index: imagefield.install
===================================================================
--- imagefield.install
+++ imagefield.install
@@ -239,8 +239,8 @@
   }
   else {
     // Cleanup the old columns.
-    db_query('ALTER TABLE {'. $table .'} DROP COLUMN '. $col_alt);
-    db_query('ALTER TABLE {'. $table .'} DROP COLUMN '. $col_title);
+    db_query('ALTER TABLE {'. $table .'} DROP COLUMN if exists '. $col_alt);
+    db_query('ALTER TABLE {'. $table .'} DROP COLUMN if exists '. $col_title);
 
     // Process to next field.
     $context['sandbox']['progress']++;