diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 000000000..8cfd55151
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,5 @@
+# Contributing to Blockly
+
+Please make pull requests against develop, not master.  If your patch needs to go into master immediately, include a note in your PR.
+
+For more information, head over to the [Blockly Developers site](https://developers.google.com/blockly/guides/modify/contributing).
diff --git a/core/workspace.js b/core/workspace.js
index db7415753..a8e97c04b 100644
--- a/core/workspace.js
+++ b/core/workspace.js
@@ -322,9 +322,12 @@ Blockly.Workspace.prototype.deleteVariable = function(name) {
           return;
         }
       }
-      window.confirm(
+      var ok = window.confirm(
           Blockly.Msg.DELETE_VARIABLE_CONFIRMATION.replace('%1', uses.length).
           replace('%2', name));
+      if (!ok) {
+        return;
+      }
     }
 
     Blockly.Events.setGroup(true);