diff --git a/histogram/histogram_test.go b/histogram/histogram_test.go
index 0575ebe..2a2d057 100644
--- a/histogram/histogram_test.go
+++ b/histogram/histogram_test.go
@@ -25,7 +25,7 @@
 	}
 
 	if g := count(h.Bins()); g != numPoints {
-		t.Fatalf("binned %d points, wanted %d", g, numPoints)
+		t.Fatalf("binned %d points, wanted %f", g, numPoints)
 	}
 }