diff --git a/gtsam/inference/MetisIndex-inl.h b/gtsam/inference/MetisIndex-inl.h
index 646523372..672036373 100644
--- a/gtsam/inference/MetisIndex-inl.h
+++ b/gtsam/inference/MetisIndex-inl.h
@@ -44,7 +44,7 @@ void MetisIndex::augment(const FACTORGRAPH& factors) {
       for(const Key& key: *factors[i]) {
         keySet.insert(keySet.end(), key); // Keep a track of all unique keys
         if (intKeyBMap_.left.find(key) == intKeyBMap_.left.end()) {
-          intKeyBMap_.insert(bm_type::value_type(key, keyCounter));
+          intKeyBMap_.insert(key, keyCounter);
           keyCounter++;
         }
       }
diff --git a/gtsam/inference/MetisIndex.h b/gtsam/inference/MetisIndex.h
index 4b1f3dfce..abdf11c5f 100644
--- a/gtsam/inference/MetisIndex.h
+++ b/gtsam/inference/MetisIndex.h
@@ -22,17 +22,9 @@
 #include <gtsam/base/types.h>
 #include <gtsam/base/timing.h>
 
-// Boost bimap generates many ugly warnings in CLANG
-#ifdef __clang__
-#  pragma clang diagnostic push
-#  pragma clang diagnostic ignored "-Wredeclared-class-member"
-#endif
-#include <boost/bimap.hpp>
-#ifdef __clang__
-#  pragma clang diagnostic pop
-#endif
-
 #include <vector>
+#include <map>
+#include <unordered_map>
 
 namespace gtsam {
 /**
@@ -45,12 +37,21 @@ namespace gtsam {
 class GTSAM_EXPORT MetisIndex {
 public:
   typedef std::shared_ptr<MetisIndex> shared_ptr;
-  typedef boost::bimap<Key, int32_t> bm_type;
 
 private:
+  // Stores Key <-> integer value relationship
+ struct BiMap {
+   std::map<Key, int32_t> left;
+   std::unordered_map<int32_t, Key> right;
+   void insert(const Key& left_value, const int32_t& right_value) {
+     left[left_value] = right_value;
+     right[right_value] = left_value;
+   }
+ };
+
   std::vector<int32_t> xadj_; // Index of node's adjacency list in adj
   std::vector<int32_t> adj_; // Stores ajacency lists of all nodes, appended into a single vector
-  boost::bimap<Key, int32_t> intKeyBMap_; // Stores Key <-> integer value relationship
+  BiMap intKeyBMap_; // Stores Key <-> integer value relationship
   size_t nKeys_;
 
 public: