diff --git a/gtsam_unstable/slam/PartialPriorFactor.h b/gtsam_unstable/slam/PartialPriorFactor.h
index 8d6fcc33b..9cd9479e1 100644
--- a/gtsam_unstable/slam/PartialPriorFactor.h
+++ b/gtsam_unstable/slam/PartialPriorFactor.h
@@ -78,7 +78,7 @@ namespace gtsam {
     /** Indices Constructor: specify the mask with a set of indices */
     PartialPriorFactor(Key key, const std::vector<size_t>& mask, const Vector& prior,
         const SharedNoiseModel& model) :
-      Base(model, key), prior_(prior), mask_(mask), H_(zeros(mask.size(), T::Dim())) {
+      Base(model, key), prior_(prior), mask_(mask), H_(zeros(mask.size(), T::dimension)) {
       assert((size_t)prior_.size() == mask.size());
       assert(model->dim() == (size_t) prior.size());
       this->fillH();