diff --git a/src/grid.cc b/src/grid.cc
index 79d72900..44a882aa 100644
--- a/src/grid.cc
+++ b/src/grid.cc
@@ -1,6 +1,11 @@
 #include "grid.h"
 
 namespace Eigen {
+		size_t hash_value(Vector3f const &v) {
+			size_t seed = 0;
+			for (int i=0;i<3;i++) boost::hash_combine(seed, v[i]);
+			return seed;
+		}
 		size_t hash_value(Vector3d const &v) {
 			size_t seed = 0;
 			for (int i=0;i<3;i++) boost::hash_combine(seed, v[i]);
diff --git a/src/grid.h b/src/grid.h
index e3db9a43..f467ba3c 100644
--- a/src/grid.h
+++ b/src/grid.h
@@ -90,6 +90,7 @@ public:
 typedef Eigen::Matrix<int64_t, 3, 1> Vector3l;
 
 namespace Eigen {
+	size_t hash_value(Vector3f const &v);
 	size_t hash_value(Vector3d const &v);
 	size_t hash_value(Vector3l const &v);
 }