diff --git a/utils.h b/utils.h
index 22aeba2..12197e8 100644
--- a/utils.h
+++ b/utils.h
@@ -103,9 +103,8 @@
 // otherwise, in which case the state of the output container is unknown.
 bool ReadPipe(const std::string& cmd, std::string* out_p);
 
-// Returns the size of the block device at path, or the file descriptor fd. If
-// an error occurs, -1 is returned.
-off_t BlockDevSize(const std::string& path);
+// Returns the size of the block device at the file descriptor fd. If an error
+// occurs, -1 is returned.
 off_t BlockDevSize(int fd);
 
 // Returns the size of the file at path, or the file desciptor fd. If the file