diff --git a/SparkleLib/Git/SparkleRepoGit.cs b/SparkleLib/Git/SparkleRepoGit.cs
index 62bd89f7..a81fad71 100644
--- a/SparkleLib/Git/SparkleRepoGit.cs
+++ b/SparkleLib/Git/SparkleRepoGit.cs
@@ -320,8 +320,10 @@ namespace SparkleLib {
                     git_theirs.Start ();
                     git_theirs.WaitForExit ();
 
-                    // Append a timestamp to local version
-                    string timestamp            = DateTime.Now.ToString ("HH:mm MMM d");
+                    // Append a timestamp to local version.
+                    // Windows doesn't allow colons in the file name, so
+                    // we use "h" between the hours and minutes instead.
+                    string timestamp            = DateTime.Now.ToString ("HH\\hmm MMM d");
                     string their_path           = conflicting_path + " (" + SparkleConfig.DefaultConfig.User.Name + ", " + timestamp + ")";
                     string abs_conflicting_path = Path.Combine (LocalPath, conflicting_path);
                     string abs_their_path       = Path.Combine (LocalPath, their_path);