diff --git a/internal/dropbox/client.go b/internal/dropbox/client.go
index 0cbadae..b981c3f 100644
--- a/internal/dropbox/client.go
+++ b/internal/dropbox/client.go
@@ -143,7 +143,8 @@ func (c *Client) Upload(path, content, mode string) (*files.FileMetadata, error)
 		commitInfo.Mode = &files.WriteMode{Tagged: dropbox.Tagged{Tag: "add"}}
 	}
 	commitInfo.Autorename = true
-	now := time.Now().UTC()
+	// Truncate to seconds - Dropbox API doesn't accept subsecond precision
+	now := time.Now().UTC().Truncate(time.Second)
 	commitInfo.ClientModified = &now
 
 	reader := bytes.NewReader(data)