diff --git a/spec/app/config-panel-spec.coffee b/spec/app/config-panel-spec.coffee
index dd231eb2f..a1f9dabed 100644
--- a/spec/app/config-panel-spec.coffee
+++ b/spec/app/config-panel-spec.coffee
@@ -73,8 +73,10 @@ describe "ConfigPanel", ->
     expect(config.get('foo.float')).toBe 3.3
     expect(config.get('foo.string')).toBe 'All limitations are self imposed.'
 
-    panel.intEditor.setText('')
-    panel.floatEditor.setText('ha ha')
+    panel.intEditor.setText('not an int')
+    panel.floatEditor.setText('not a float')
+    panel.stringEditor.setText('')
     window.advanceClock(10000) # wait for contents-modified to be triggered
     expect(config.get('foo.int')).toBe 0
     expect(config.get('foo.float')).toBe 0
+    expect(config.get('foo.string')).toBe undefined
diff --git a/src/app/config-panel.coffee b/src/app/config-panel.coffee
index 31b76b8b1..d884cea7d 100644
--- a/src/app/config-panel.coffee
+++ b/src/app/config-panel.coffee
@@ -43,4 +43,5 @@ class ConfigPanel extends View
           value = editor.getText()
           if type == 'int' then value = parseInt(value) or 0
           if type == 'float' then value = parseFloat(value) or 0
+          if value == "" then value = undefined
           config.set name, value