diff --git a/src/lib.rs b/src/lib.rs
index 8a3c6e3..fcc66df 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -748,7 +748,7 @@ mod test {
         // The zip archive uses as BufReader which reads in chunks of 8192. To ensure we prefetch
         // enough data we round the size up to the nearest multiple of the buffer size.
         let buffer_size = 8192;
-        let size = ((size + buffer_size - 1) / buffer_size) * buffer_size;
+        let size = size.div_ceil(buffer_size) * buffer_size;
 
         // Fetch the bytes from the zip archive that contain the requested file.
         reader