diff --git a/.replit b/.replit
deleted file mode 100644
index 58432e9..0000000
--- a/.replit
+++ /dev/null
@@ -1,2 +0,0 @@
-language = "rust"
-run = "cargo test"
\ No newline at end of file
diff --git a/libips/src/repository/catalog.rs b/libips/src/repository/catalog.rs
index 5d64fae..fd22d3e 100644
--- a/libips/src/repository/catalog.rs
+++ b/libips/src/repository/catalog.rs
@@ -66,7 +66,8 @@ pub type Result<T> = std::result::Result<T, CatalogError>;
 /// Format a SystemTime as an ISO-8601 'basic format' date in UTC
 pub fn format_iso8601_basic(time: &SystemTime) -> String {
     let datetime = convert_system_time_to_datetime(time);
-    format!("{}Z", datetime.format("%Y%m%dT%H%M%S.%f"))
+    let micros = datetime.timestamp_subsec_micros();
+    format!("{}.{:06}Z", datetime.format("%Y%m%dT%H%M%S"), micros)
 }
 
 /// Convert SystemTime to UTC DateTime, handling errors gracefully
diff --git a/libips/src/repository/catalog_writer.rs b/libips/src/repository/catalog_writer.rs
index d07b997..9ecc149 100644
--- a/libips/src/repository/catalog_writer.rs
+++ b/libips/src/repository/catalog_writer.rs
@@ -20,18 +20,18 @@ struct PythonFormatter;
 impl Formatter for PythonFormatter {
     fn begin_object_key<W: ?Sized + Write>(&mut self, writer: &mut W, first: bool) -> std::io::Result<()> {
         if !first {
-            writer.write_all(b", ")?;
+            writer.write_all(b",")?;
         }
         Ok(())
     }
 
     fn begin_object_value<W: ?Sized + Write>(&mut self, writer: &mut W) -> std::io::Result<()> {
-        writer.write_all(b": ")
+        writer.write_all(b":")
     }
 
     fn begin_array_value<W: ?Sized + Write>(&mut self, writer: &mut W, first: bool) -> std::io::Result<()> {
         if !first {
-            writer.write_all(b", ")?;
+            writer.write_all(b",")?;
         }
         Ok(())
     }
diff --git a/libips/src/repository/file_backend.rs b/libips/src/repository/file_backend.rs
index c4aa66c..00dc895 100644
--- a/libips/src/repository/file_backend.rs
+++ b/libips/src/repository/file_backend.rs
@@ -2520,7 +2520,7 @@ impl FileBackend {
                 );
             }
 
-            let _ = catalog_writer::write_update_log(&update_log_path, &mut update_log)?;
+            let update_log_sig = catalog_writer::write_update_log(&update_log_path, &mut update_log)?;
             debug!("Wrote update log file");
 
             // Add an update log to catalog.attrs
@@ -2529,7 +2529,7 @@ impl FileBackend {
                 update_log_name.clone(),
                 crate::repository::catalog::UpdateLogInfo {
                     last_modified: timestamp.clone(),
-                    signature_sha1: None,
+                    signature_sha1: Some(update_log_sig),
                 },
             );