diff --git a/blocks/loops.js b/blocks/loops.js
index a8463be89..9509f3c9d 100644
--- a/blocks/loops.js
+++ b/blocks/loops.js
@@ -142,6 +142,7 @@ Blockly.Blocks['controls_for'] = {
         {
           "type": "input_value",
           "name": "TO",
+          "check": "Number",
           "align": "RIGHT"
         },
         {
diff --git a/blocks_compressed.js b/blocks_compressed.js
index 29ccf3570..a890f5385 100644
--- a/blocks_compressed.js
+++ b/blocks_compressed.js
@@ -60,7 +60,7 @@ Blockly.Blocks.loops={};Blockly.Blocks.loops.HUE=120;Blockly.Blocks.controls_rep
 Blockly.Blocks.controls_repeat_ext={init:function(){this.jsonInit({message:Blockly.Msg.CONTROLS_REPEAT_TITLE,args:[{type:"input_value",name:"TIMES",check:"Number"}],previousStatement:null,nextStatement:null,colour:Blockly.Blocks.loops.HUE,tooltip:Blockly.Msg.CONTROLS_REPEAT_TOOLTIP,helpUrl:Blockly.Msg.CONTROLS_REPEAT_HELPURL});this.appendStatementInput("DO").appendField(Blockly.Msg.CONTROLS_REPEAT_INPUT_DO)}};
 Blockly.Blocks.controls_whileUntil={init:function(){var a=[[Blockly.Msg.CONTROLS_WHILEUNTIL_OPERATOR_WHILE,"WHILE"],[Blockly.Msg.CONTROLS_WHILEUNTIL_OPERATOR_UNTIL,"UNTIL"]];this.setHelpUrl(Blockly.Msg.CONTROLS_WHILEUNTIL_HELPURL);this.setColour(Blockly.Blocks.loops.HUE);this.appendValueInput("BOOL").setCheck("Boolean").appendField(new Blockly.FieldDropdown(a),"MODE");this.appendStatementInput("DO").appendField(Blockly.Msg.CONTROLS_WHILEUNTIL_INPUT_DO);this.setPreviousStatement(!0);this.setNextStatement(!0);
 var b=this;this.setTooltip(function(){var a=b.getFieldValue("MODE");return{WHILE:Blockly.Msg.CONTROLS_WHILEUNTIL_TOOLTIP_WHILE,UNTIL:Blockly.Msg.CONTROLS_WHILEUNTIL_TOOLTIP_UNTIL}[a]})}};
-Blockly.Blocks.controls_for={init:function(){this.jsonInit({message:Blockly.Msg.CONTROLS_FOR_TITLE,args:[{type:"field_variable",name:"VAR",variable:null},{type:"input_value",name:"FROM",check:"Number",align:"RIGHT"},{type:"input_value",name:"TO",align:"RIGHT"},{type:"input_value",name:"BY",check:"Number",align:"RIGHT"}],inputsInline:!0,previousStatement:null,nextStatement:null,colour:Blockly.Blocks.loops.HUE,helpUrl:Blockly.Msg.CONTROLS_FOR_HELPURL});this.appendStatementInput("DO").appendField(Blockly.Msg.CONTROLS_FOR_INPUT_DO);
+Blockly.Blocks.controls_for={init:function(){this.jsonInit({message:Blockly.Msg.CONTROLS_FOR_TITLE,args:[{type:"field_variable",name:"VAR",variable:null},{type:"input_value",name:"FROM",check:"Number",align:"RIGHT"},{type:"input_value",name:"TO",check:"Number",align:"RIGHT"},{type:"input_value",name:"BY",check:"Number",align:"RIGHT"}],inputsInline:!0,previousStatement:null,nextStatement:null,colour:Blockly.Blocks.loops.HUE,helpUrl:Blockly.Msg.CONTROLS_FOR_HELPURL});this.appendStatementInput("DO").appendField(Blockly.Msg.CONTROLS_FOR_INPUT_DO);
 var a=this;this.setTooltip(function(){return Blockly.Msg.CONTROLS_FOR_TOOLTIP.replace("%1",a.getFieldValue("VAR"))})},getVars:function(){return[this.getFieldValue("VAR")]},renameVar:function(a,b){Blockly.Names.equals(a,this.getFieldValue("VAR"))&&this.setFieldValue(b,"VAR")},customContextMenu:function(a){if(!this.isCollapsed()){var b={enabled:!0},c=this.getFieldValue("VAR");b.text=Blockly.Msg.VARIABLES_SET_CREATE_GET.replace("%1",c);c=goog.dom.createDom("field",null,c);c.setAttribute("name","VAR");
 c=goog.dom.createDom("block",null,c);c.setAttribute("type","variables_get");b.callback=Blockly.ContextMenu.callbackFactory(this,c);a.push(b)}}};
 Blockly.Blocks.controls_forEach={init:function(){this.jsonInit({message:Blockly.Msg.CONTROLS_FOREACH_TITLE,args:[{type:"field_variable",name:"VAR",variable:null},{type:"input_value",name:"LIST",check:"Array"}],previousStatement:null,nextStatement:null,colour:Blockly.Blocks.loops.HUE,helpUrl:Blockly.Msg.CONTROLS_FOREACH_HELPURL});this.appendStatementInput("DO").appendField(Blockly.Msg.CONTROLS_FOREACH_INPUT_DO);var a=this;this.setTooltip(function(){return Blockly.Msg.CONTROLS_FOREACH_TOOLTIP.replace("%1",