diff --git a/wire/core/Fields.php b/wire/core/Fields.php
index 8efd9b38..5281507f 100644
--- a/wire/core/Fields.php
+++ b/wire/core/Fields.php
@@ -337,6 +337,10 @@ class Fields extends WireSaveableItems {
 			// even if only the case has changed. 
 			$schema = $item->type->getDatabaseSchema($item);
 			if(!empty($schema)) {
+				foreach(array($table, "tmp_$table") as $t) {
+					if(!$database->tableExists($t)) continue;
+					throw new WireException("Cannot rename to '$item->name' because table `$table` already exists");
+				}
 				$database->exec("RENAME TABLE `$prevTable` TO `tmp_$table`"); // QA
 				$database->exec("RENAME TABLE `tmp_$table` TO `$table`"); // QA
 			}
@@ -1488,4 +1492,3 @@ class Fields extends WireSaveableItems {
 	}
 
 }
-