diff --git a/histogram.h b/histogram.h
index 08d8e34..d1b1414 100644
--- a/histogram.h
+++ b/histogram.h
@@ -2,7 +2,8 @@
 #define HISTOGRAM_H_INCLUDED
 
 #include <vector>
-
+std::vector<size_t>
+make_histogram(const std::vector<double> numbers, size_t bin_count);
 #endif // HISTOGRAM_H_INCLUDED