diff --git a/gtsam_unstable/nonlinear/BADFactor.h b/gtsam_unstable/nonlinear/BADFactor.h
index 3afb3cc7e..6780afd73 100644
--- a/gtsam_unstable/nonlinear/BADFactor.h
+++ b/gtsam_unstable/nonlinear/BADFactor.h
@@ -64,7 +64,7 @@ public:
 
   /// get the dimension of the factor (number of rows on linearization)
   size_t dim() const {
-    return 0;
+    return measurement_.dim();
   }
 
   /// linearize to a GaussianFactor