diff --git a/blocks/math.js b/blocks/math.js
index d7950f94da..04db90ee10 100644
--- a/blocks/math.js
+++ b/blocks/math.js
@@ -38,15 +38,14 @@ Blockly.Blocks.math.HUE = Blockly.Colours.textField;
 
 Blockly.Blocks['math_number'] = {
   /**
-   * Block for numeric value.
+   * Block for generic numeric value.
    * @this Blockly.Block
    */
   init: function() {
     this.setHelpUrl(Blockly.Msg.MATH_NUMBER_HELPURL);
     this.setColour(Blockly.Blocks.math.HUE);
     this.appendDummyInput()
-        .appendField(new Blockly.FieldNumber('0',
-        Blockly.FieldTextInput.numberValidator, 20, -Infinity, Infinity), 'NUM');
+        .appendField(new Blockly.FieldNumber('0', true, true), 'NUM');
     this.setOutput(true, 'Number');
     // Assign 'this' to a variable for use in the tooltip closure below.
     var thisBlock = this;
@@ -61,30 +60,28 @@ Blockly.Blocks['math_number'] = {
 
 Blockly.Blocks['math_whole_number'] = {
   /**
-   * Block for whole number value, with min of 0 and max Infinity, precision 0.
+   * Block for whole number value, no negatives or decimals.
    * @this Blockly.Block
    */
   init: function() {
     this.setHelpUrl(Blockly.Msg.MATH_NUMBER_HELPURL);
     this.setColour(Blockly.Blocks.math.HUE);
     this.appendDummyInput()
-        .appendField(new Blockly.FieldNumber('0',
-        Blockly.FieldNumber.numberValidator, 0, 0, Infinity), 'NUM');
+        .appendField(new Blockly.FieldNumber('0', false, false), 'NUM');
     this.setOutput(true, 'Number');
   }
 };
 
 Blockly.Blocks['math_positive_number'] = {
   /**
-   * Block for positive number value, with min of 0 and max Infinity, precision 20.
+   * Block for positive number value, with decimal.
    * @this Blockly.Block
    */
   init: function() {
     this.setHelpUrl(Blockly.Msg.MATH_NUMBER_HELPURL);
     this.setColour(Blockly.Blocks.math.HUE);
     this.appendDummyInput()
-        .appendField(new Blockly.FieldNumber('0',
-        Blockly.FieldNumber.numberValidator, 20, 0, Infinity), 'NUM');
+        .appendField(new Blockly.FieldNumber('0', true, false), 'NUM');
     this.setOutput(true, 'Number');
   }
 };
diff --git a/core/block_render_svg_vertical.js b/core/block_render_svg_vertical.js
index 40b65ac330..61950e281c 100644
--- a/core/block_render_svg_vertical.js
+++ b/core/block_render_svg_vertical.js
@@ -324,7 +324,7 @@ Blockly.BlockSvg.FIELD_WIDTH_MIN_EDIT = 8 * Blockly.BlockSvg.GRID_UNIT;
  * Maximum width of user inputs during editing
  * @const
  */
-Blockly.BlockSvg.FIELD_WIDTH_MAX_EDIT = 52 * Blockly.BlockSvg.GRID_UNIT;
+Blockly.BlockSvg.FIELD_WIDTH_MAX_EDIT = Infinity;
 
 /**
  * Maximum height of user inputs during editing
diff --git a/core/field_number.js b/core/field_number.js
index e1d62ee3dd..e82b1e2d1b 100644
--- a/core/field_number.js
+++ b/core/field_number.js
@@ -31,24 +31,41 @@ goog.require('goog.math');
 goog.require('goog.userAgent');
 
 
+/**
+ * Return an appropriate restrictor, depending on whether this FieldNumber
+ * allows decimal or negative numbers.
+ * @param {boolean} decimalAllowed Whether number may have decimal/float component.
+ * @param {boolean} negativeAllowed Whether number may be negative.
+ * @return {!RegExp} Regular expression for this FieldNumber's restrictor.
+ */
+var getNumRestrictor = function(decimalAllowed, negativeAllowed) {
+  var pattern = "[\\d]|[e]"; // Always allow digits and e, from Scratch 2.0.
+  if (decimalAllowed) {
+    pattern += "|[\\.]";
+  }
+  if (negativeAllowed) {
+    pattern += "|[-]";
+  }
+  return new RegExp(pattern);
+};
+
 /**
  * Class for an editable number field.
  * @param {string} text The initial content of the field.
+ * @param {boolean} decimalAllowed Whether number may have decimal/float component.
+ * @param {boolean} negativeAllowed Whether number may be negative.
  * @param {Function=} opt_validator An optional function that is called
  *     to validate any constraints on what the user entered.  Takes the new
  *     text as an argument and returns the accepted text or null to abort
  *     the change.
- * @param {number} precision Precision of the decimal value (negative power of 10).
- * @param {number} min Minimum value of the number.
- * @param {number} max Maximum value of the number.
  * @extends {Blockly.FieldTextInput}
  * @constructor
  */
-Blockly.FieldNumber = function(text, opt_validator, precision, min, max) {
-  this.precision_ = precision;
-  this.min_ = min;
-  this.max_ = max;
-  Blockly.FieldNumber.superClass_.constructor.call(this, text, opt_validator);
+Blockly.FieldNumber = function(text, decimalAllowed, negativeAllowed, opt_validator) {
+  this.decimalAllowed_ = decimalAllowed;
+  this.negativeAllowed_ = negativeAllowed;
+  var numRestrictor = getNumRestrictor(decimalAllowed, negativeAllowed);
+  Blockly.FieldNumber.superClass_.constructor.call(this, text, opt_validator, numRestrictor);
 };
 goog.inherits(Blockly.FieldNumber, Blockly.FieldTextInput);
 
@@ -101,37 +118,6 @@ Blockly.FieldNumber.NUMPAD_DELETE_ICON = 'data:image/svg+xml;utf8,' +
  */
 Blockly.FieldNumber.activeField_ = null;
 
-/**
- * Sets a new change handler for angle field.
- * @param {Function} handler New change handler, or null.
- */
-Blockly.FieldNumber.prototype.setValidator = function(handler) {
-  var wrappedHandler;
-  if (handler) {
-    // Wrap the user's change handler together with the number validator.
-    // This is copied entirely from FieldAngle.
-    wrappedHandler = function(value) {
-      var v1 = handler.call(this, value);
-      var v2;
-      if (v1 === null) {
-        v2 = v1;
-      } else {
-        if (v1 === undefined) {
-          v1 = value;
-        }
-        v2 = Blockly.FieldNumber.numberValidator.call(this, v1);
-        if (v2 === undefined) {
-          v2 = v1;
-        }
-      }
-      return v2 === value ? undefined : v2;
-    };
-  } else {
-    wrappedHandler = Blockly.FieldNumber.numberValidator;
-  }
-  Blockly.FieldNumber.superClass_.setValidator.call(this, wrappedHandler);
-};
-
 /**
  * Show the inline free-text editor on top of the text and the num-pad if appropriate.
  * @private
@@ -170,7 +156,7 @@ Blockly.FieldNumber.prototype.showNumPad_ = function() {
     button.innerHTML = buttonText;
     Blockly.bindEvent_(button, 'mousedown', button,
 	Blockly.FieldNumber.numPadButtonTouch_);
-    if (buttonText == '.' && this.precision_ == 0) {
+    if (buttonText == '.' && !this.decimalAllowed) {
       // Don't show the decimal point for inputs that must be round numbers
       button.setAttribute('style', 'visibility: hidden');
     }
@@ -267,27 +253,6 @@ Blockly.FieldNumber.prototype.onHide_ = function() {
   Blockly.DropDownDiv.content_.removeAttribute('aria-haspopup');
 };
 
-/**
- * Ensure that only a number may be entered with the properties of this field.
- * @param {string} text The user's text.
- * @return {?string} A string representing a valid angle, or null if invalid.
- */
-Blockly.FieldNumber.numberValidator = function(text) {
-  var n = Blockly.FieldTextInput.numberValidator(text);
-  if (n !== null) {
-    // string -> float
-    n = parseFloat(n);
-    // Keep within min and max
-    n = Math.min(Math.max(n, this.min_), this.max_);
-    // Update float precision (returns a string)
-    n = n.toFixed(this.precision_);
-    // Parse to a float and back to string to remove trailing decimals
-    n = parseFloat(n);
-    n = String(n);
-  }
-  return n;
-};
-
 /**
  * Border radius for drawing this field, called when rendering the owning shadow block.
  * @return {Number} Border radius in px.
diff --git a/core/field_textinput.js b/core/field_textinput.js
index 6f0b416510..3dea4dfdcc 100644
--- a/core/field_textinput.js
+++ b/core/field_textinput.js
@@ -43,12 +43,16 @@ goog.require('goog.userAgent');
  *     to validate any constraints on what the user entered.  Takes the new
  *     text as an argument and returns either the accepted text, a replacement
  *     text, or null to abort the change.
+ * @param {RegExp=} opt_restrictor An optional regular expression to restrict
+ *     typed text to. Text that doesn't match the restrictor will never show
+ *     in the text field.
  * @extends {Blockly.Field}
  * @constructor
  */
-Blockly.FieldTextInput = function(text, opt_validator) {
+Blockly.FieldTextInput = function(text, opt_validator, opt_restrictor) {
   Blockly.FieldTextInput.superClass_.constructor.call(this, text,
       opt_validator);
+  this.setRestrictor(opt_restrictor);
 };
 goog.inherits(Blockly.FieldTextInput, Blockly.Field);
 
@@ -109,6 +113,15 @@ Blockly.FieldTextInput.prototype.setSpellcheck = function(check) {
   this.spellcheck_ = check;
 };
 
+/**
+ * Set the restrictor regex for this text input.
+ * Text that doesn't match the restrictor will never show in the text field.
+ * @param {?RegExp} restrictor Regular expression to restrict text.
+ */
+Blockly.FieldTextInput.prototype.setRestrictor = function(restrictor) {
+  this.restrictor_ = restrictor;
+};
+
 /**
  * Show the inline free-text editor on top of the text.
  * @param {boolean=} opt_quietInput True if editor should be created without
@@ -208,6 +221,15 @@ Blockly.FieldTextInput.prototype.onHtmlInputKeyDown_ = function(e) {
  * @private
  */
 Blockly.FieldTextInput.prototype.onHtmlInputChange_ = function(e) {
+  // Check if the key matches the restrictor.
+  if (e.type === 'keypress' && this.restrictor_) {
+    var charCode = String.fromCharCode(e.keyCode);
+    if (!this.restrictor_.test(charCode) && e.preventDefault) {
+      // Failed to pass restrictor.
+      e.preventDefault();
+      return;
+    }
+  }
   var htmlInput = Blockly.FieldTextInput.htmlInput_;
   // Update source block.
   var text = htmlInput.value;
diff --git a/tests/vertical_playground.html b/tests/vertical_playground.html
index 2f77647957..e33847df62 100644
--- a/tests/vertical_playground.html
+++ b/tests/vertical_playground.html
@@ -318,15 +318,15 @@
       <category name="Control">
         <block type="control_wait">
           <value name="DURATION">
-            <shadow type="math_number">
+            <shadow type="math_positive_number">
               <field name="NUM">1</field>
             </shadow>
           </value>
         </block>
         <block type="control_repeat">
           <value name="TIMES">
-            <shadow type="math_number">
-              <field name="NUM">4</field>
+            <shadow type="math_whole_number">
+              <field name="NUM">10</field>
             </shadow>
           </value>
         </block>
@@ -468,7 +468,7 @@
           </block>
           <block type="operator_letter_of">
             <value name="LETTER">
-              <shadow type="math_number">
+              <shadow type="math_whole_number">
                 <field name="NUM">1</field>
               </shadow>
             </value>