diff --git a/src/observe.js b/src/observe.js
index 4cc88d7..07d6829 100644
--- a/src/observe.js
+++ b/src/observe.js
@@ -364,7 +364,7 @@
         this.callback.apply(this.target, args);
       } catch (ex) {
         Observer._errorThrownDuringCallback = true;
-        console.error('Exception caught during observer callback: ' + ex);
+        console.error('Exception caught during observer callback: ' + (ex.stack || ex));
       }
     },