diff --git a/src/ZLogger/Providers/RollingFilestream.cs b/src/ZLogger/Providers/RollingFilestream.cs
index a0e8de6a..a3865a8b 100644
--- a/src/ZLogger/Providers/RollingFilestream.cs
+++ b/src/ZLogger/Providers/RollingFilestream.cs
@@ -31,7 +31,7 @@ public RollingFileStream(Func<DateTimeOffset, int, string> fileNameSelector, Rol
     {
         this.fileNameSelector = fileNameSelector;
         this.rollInterval = rollInterval;
-        this.rollSizeInBytes = rollSizeKB * 1024;
+        this.rollSizeInBytes = (long)rollSizeKB * 1024;
         this.timeProvider = timeProvider;
         this.fileShared = fileShared;