diff --git a/gtsam/inference/ClusterTree-inst.h b/gtsam/inference/ClusterTree-inst.h
index b76430c20..bbe878907 100644
--- a/gtsam/inference/ClusterTree-inst.h
+++ b/gtsam/inference/ClusterTree-inst.h
@@ -123,6 +123,62 @@ void ClusterTree<BAYESTREE, GRAPH>::Cluster::print(const std::string& s,
   PrintKeyVector(orderedFrontalKeys);
 }
 
+/* ************************************************************************* */
+template<class BAYESTREE, class GRAPH>
+void ClusterTree<BAYESTREE, GRAPH>::Cluster::mergeChildren(
+    const std::vector<bool>& merge) {
+  gttic(Cluster::mergeChildren);
+  size_t nrChildren = children.size();
+
+  // Count how many keys, factors and children we'll end up with
+  size_t nrKeys = orderedFrontalKeys.size();
+  size_t nrFactors = factors.size();
+  size_t nrNewChildren = 0;
+  // Loop over children
+  for (size_t i = 0; i < nrChildren; ++i) {
+    if (merge[i]) {
+      // Get a reference to the i, adjusting the index to account for children
+      // previously merged and removed from the i list.
+      sharedNode child = children[i];
+      nrKeys += child->orderedFrontalKeys.size();
+      nrFactors += child->factors.size();
+      nrNewChildren += child->children.size();
+    } else {
+      nrNewChildren += 1; // we keep the child
+    }
+  }
+
+  // now reserve space, and really merge
+  orderedFrontalKeys.reserve(nrKeys);
+  factors.reserve(nrFactors);
+  typename Node::Children newChildren;
+  newChildren.reserve(nrNewChildren);
+  // Loop over newChildren
+  for (size_t i = 0; i < nrChildren; ++i) {
+    // Check if we should merge the i^th child
+    sharedNode child = children[i];
+    if (merge[i]) {
+      // Get a reference to the i, adjusting the index to account for newChildren
+      // previously merged and removed from the i list.
+      // Merge keys. For efficiency, we add keys in reverse order at end, calling reverse after..
+      orderedFrontalKeys.insert(orderedFrontalKeys.end(),
+          child->orderedFrontalKeys.rbegin(), child->orderedFrontalKeys.rend());
+      // Merge keys, factors, and children.
+      factors.insert(factors.end(), child->factors.begin(),
+          child->factors.end());
+      newChildren.insert(newChildren.end(), child->children.begin(),
+          child->children.end());
+      // Increment problem size
+      problemSize_ = std::max(problemSize_, child->problemSize_);
+      // Increment number of frontal variables
+    } else {
+      newChildren.push_back(child); // we keep the child
+    }
+  }
+  children = newChildren;
+  std::reverse(orderedFrontalKeys.begin(), orderedFrontalKeys.end());
+}
+
 /* ************************************************************************* */
 template<class BAYESTREE, class GRAPH>
 void ClusterTree<BAYESTREE, GRAPH>::print(const std::string& s,
diff --git a/gtsam/inference/ClusterTree.h b/gtsam/inference/ClusterTree.h
index 0b98d3e36..b00532d22 100644
--- a/gtsam/inference/ClusterTree.h
+++ b/gtsam/inference/ClusterTree.h
@@ -55,64 +55,12 @@ public:
       return problemSize_;
     }
 
-    /** print this node */
+    /// print this node
     void print(const std::string& s = "", const KeyFormatter& keyFormatter =
         DefaultKeyFormatter) const;
 
-    void mergeChildren(const std::vector<bool>& merge) {
-      gttic(merge_children);
-      size_t nrChildren = children.size();
-
-      // Count how many keys, factors and children we'll end up with
-      size_t nrKeys = this->orderedFrontalKeys.size();
-      size_t nrFactors = this->factors.size();
-      size_t nrNewChildren = 0;
-      // Loop over children
-      for (size_t i = 0; i < nrChildren; ++i) {
-        if (merge[i]) {
-          // Get a reference to the i, adjusting the index to account for children
-          // previously merged and removed from the i list.
-          sharedNode child = this->children[i];
-          nrKeys += child->orderedFrontalKeys.size();
-          nrFactors += child->factors.size();
-          nrNewChildren += child->children.size();
-        } else {
-          nrNewChildren += 1; // we keep the child
-        }
-      }
-
-      // now reserve space, and really merge
-      this->orderedFrontalKeys.reserve(nrKeys);
-      this->factors.reserve(nrFactors);
-      typename Node::Children newChildren;
-      newChildren.reserve(nrNewChildren);
-      // Loop over newChildren
-      for (size_t i = 0; i < nrChildren; ++i) {
-        // Check if we should merge the i^th child
-        sharedNode child = this->children[i];
-        if (merge[i]) {
-          // Get a reference to the i, adjusting the index to account for newChildren
-          // previously merged and removed from the i list.
-          // Merge keys. For efficiency, we add keys in reverse order at end, calling reverse after..
-          this->orderedFrontalKeys.insert(this->orderedFrontalKeys.end(),
-              child->orderedFrontalKeys.rbegin(),
-              child->orderedFrontalKeys.rend());
-          // Merge keys, factors, and children.
-          this->factors.insert(this->factors.end(), child->factors.begin(),
-              child->factors.end());
-          newChildren.insert(newChildren.end(), child->children.begin(),
-              child->children.end());
-          // Increment problem size
-          problemSize_ = std::max(problemSize_, child->problemSize_);
-          // Increment number of frontal variables
-        } else {
-          newChildren.push_back(child); // we keep the child
-        }
-      }
-      this->children = newChildren;
-      std::reverse(this->orderedFrontalKeys.begin(),
-          this->orderedFrontalKeys.end());
-    }
+    /// Merge all children for which bit is set into this node
+    void mergeChildren(const std::vector<bool>& merge);
   };
 
   typedef boost::shared_ptr<Cluster> sharedCluster; ///< Shared pointer to Cluster