diff --git a/RELEASE_NOTES.rst b/RELEASE_NOTES.rst
index d154dbeb1..9ed10217b 100644
--- a/RELEASE_NOTES.rst
+++ b/RELEASE_NOTES.rst
@@ -32,6 +32,8 @@ unreleased [2.x]
   Please always include the console output when reporting a GUI crash.
 * Closing the core device communications before pausing is done automatically.
   Experiments no longer need to do it explicitly.
+* The result folders are formatted "%Y-%m-%d/%H instead of "%Y-%m-%d/%H-%M".
+  (i.e. grouping by day and then by hour, instead of by day and then by minute)
 
 
 unreleased [1.0rc3]
diff --git a/artiq/master/worker_db.py b/artiq/master/worker_db.py
index ce0862b2b..bd34ef143 100644
--- a/artiq/master/worker_db.py
+++ b/artiq/master/worker_db.py
@@ -56,24 +56,26 @@ class RIDCounter:
             day_folders = os.listdir(self.results_dir)
         except:
             return r
-        day_folders = filter(lambda x: re.fullmatch('\d\d\d\d-\d\d-\d\d', x),
-                             day_folders)
+        day_folders = filter(
+            lambda x: re.fullmatch("\\d\\d\\d\\d-\\d\\d-\\d\\d", x),
+            day_folders)
         for df in day_folders:
             day_path = os.path.join(self.results_dir, df)
             try:
-                minute_folders = os.listdir(day_path)
+                hm_folders = os.listdir(day_path)
             except:
                 continue
-            minute_folders = filter(lambda x: re.fullmatch('\d\d-\d\d', x),
-                                    minute_folders)
-            for mf in minute_folders:
-                minute_path = os.path.join(day_path, mf)
+            hm_folders = filter(lambda x: re.fullmatch("\\d\\d(-\\d\\d)?", x),
+                                hm_folders)
+            for hmf in hm_folders:
+                hm_path = os.path.join(day_path, hmf)
                 try:
-                    h5files = os.listdir(minute_path)
+                    h5files = os.listdir(hm_path)
                 except:
                     continue
                 for x in h5files:
-                    m = re.fullmatch('(\d\d\d\d\d\d\d\d\d)-.*\.h5', x)
+                    m = re.fullmatch(
+                        "(\\d\\d\\d\\d\\d\\d\\d\\d\\d)-.*\\.h5", x)
                     if m is None:
                         continue
                     rid = int(m.group(1))
diff --git a/artiq/master/worker_impl.py b/artiq/master/worker_impl.py
index 4e6731ef7..79f71eba2 100644
--- a/artiq/master/worker_impl.py
+++ b/artiq/master/worker_impl.py
@@ -211,7 +211,7 @@ def main():
                     rid, obj["pipeline_name"], expid, obj["priority"])
                 dirname = os.path.join("results",
                                        time.strftime("%Y-%m-%d", start_time),
-                                       time.strftime("%H-%M", start_time))
+                                       time.strftime("%H", start_time))
                 os.makedirs(dirname, exist_ok=True)
                 os.chdir(dirname)
                 exp_inst = exp(