diff --git a/src/main/java/com/conveyal/datatools/manager/models/FeedVersion.java b/src/main/java/com/conveyal/datatools/manager/models/FeedVersion.java
index 104383188..523ee181a 100644
--- a/src/main/java/com/conveyal/datatools/manager/models/FeedVersion.java
+++ b/src/main/java/com/conveyal/datatools/manager/models/FeedVersion.java
@@ -393,8 +393,8 @@ public void validateMobility(MonitorableJob.Status status) {
             status.update("MobilityData Analysis...", 11);
 
             // Wait for the file to be entirely copied into the directory.
-            // TODO: base this on the file being completely saved rather than a fixed amount of time.
-            Thread.sleep(5000);
+            // 5 seconds + ~1 second per 10mb
+            Thread.sleep(5000 + (this.fileSize / 10000));
             File gtfsZip = this.retrieveGtfsFile();
             // Namespace based folders avoid clash for validation being run on multiple versions of a feed.
             // TODO: do we know that there will always be a namespace?