diff --git a/lib/mysql.js b/lib/mysql.js
index b7253c9..c34c026 100644
--- a/lib/mysql.js
+++ b/lib/mysql.js
@@ -403,11 +403,13 @@ MySQL.prototype.alterTable = function (model, actualFields, actualIndexes, done,
     propNames.forEach(function (propName) {
         if (propName === 'id') return;
         var found;
-        actualFields.forEach(function (f) {
-            if (f.Field === propName) {
-                found = f;
-            }
-        });
+        if (actualFields) {
+            actualFields.forEach(function (f) {
+                if (f.Field === propName) {
+                    found = f;
+                }
+            });
+        }
 
         if (found) {
             actualize(propName, found);
@@ -417,13 +419,15 @@ MySQL.prototype.alterTable = function (model, actualFields, actualIndexes, done,
     });
 
     // drop columns
-    actualFields.forEach(function (f) {
-        var notFound = !~propNames.indexOf(f.Field);
-        if (f.Field === 'id') return;
-        if (notFound || !m.properties[f.Field]) {
-            sql.push('DROP COLUMN `' + f.Field + '`');
-        }
-    });
+    if (actualFields) {
+        actualFields.forEach(function (f) {
+            var notFound = !~propNames.indexOf(f.Field);
+            if (f.Field === 'id') return;
+            if (notFound || !m.properties[f.Field]) {
+                sql.push('DROP COLUMN `' + f.Field + '`');
+            }
+        });
+    }
 
     // remove indexes
     aiNames.forEach(function (indexName) {