diff --git a/src/pugixpath.cpp b/src/pugixpath.cpp
index d20baad..2296814 100644
--- a/src/pugixpath.cpp
+++ b/src/pugixpath.cpp
@@ -444,6 +444,7 @@ namespace
 	double round_nearest_nzero(double value)
 	{
 		// same as round_nearest, but returns -0 for [-0.5, -0]
+		// ceil is used to differentiate between +0 and -0 (we return -0 for [-0.5, -0] and +0 for +0)
 		return (value >= -0.5 && value <= 0) ? ceil(value) : floor(value + 0.5);
 	}