diff --git a/src/hamster/edit_activity.py b/src/hamster/edit_activity.py
index 47b6b7c89..318fce8db 100644
--- a/src/hamster/edit_activity.py
+++ b/src/hamster/edit_activity.py
@@ -273,11 +273,11 @@ def on_tags_changed(self, widget):
     def update_cmdline(self, select=None):
         """Update the cmdline entry content."""
         self.cmdline_fact = self.fact.copy(description=None)
-        label = self.cmdline_fact.serialized(prepend_date=False)
+        label = self.cmdline_fact.serialized(default_day=self.date)
         with self.cmdline.handler_block(self.cmdline.checker):
             self.cmdline.set_text(label)
             if select:
-                time_str = self.cmdline_fact.serialized_time(prepend_date=False)
+                time_str = self.cmdline_fact.serialized_time(default_day=self.date)
                 self.cmdline.select_region(0, len(time_str))
 
     def update_fields(self):
diff --git a/src/hamster/lib/__init__.py b/src/hamster/lib/__init__.py
index 678335ac9..91a618e9f 100644
--- a/src/hamster/lib/__init__.py
+++ b/src/hamster/lib/__init__.py
@@ -7,11 +7,12 @@
 
 from copy import deepcopy
 
-from hamster.lib.parsing import DATE_FMT, TIME_FMT, parse_fact
+from hamster.lib.parsing import DATE_FMT, TIME_FMT, DATETIME_FMT, parse_fact
 from hamster.lib.stuff import (
     datetime_to_hamsterday,
     hamsterday_time_to_datetime,
     hamster_now,
+    hamster_today,
 )
 
 
@@ -150,20 +151,31 @@ def serialized_name(self):
             res += " %s" % " ".join("#%s" % tag for tag in self.tags)
         return res
 
-    def serialized_time(self, prepend_date=True):
-        time = ""
+    def serialized_range(self, default_day=None):
+        """Return a string representing the time range.
+
+        Start date is shown only if start does not belong to default_day.
+        End date is shown only if end does not belong to
+        the same hamster day as start.
+        """
+        time_str = ""
         if self.start_time:
-            if prepend_date:
-                time += self.date.strftime(DATE_FMT) + " "
-            time += self.start_time.strftime(TIME_FMT)
+            if datetime_to_hamsterday(self.start_time) != default_day:
+                time_str += self.start_time.strftime(DATETIME_FMT)
+            else:
+                time_str += self.start_time.strftime(TIME_FMT)
         if self.end_time:
-            time = "%s-%s" % (time, self.end_time.strftime(TIME_FMT))
-        return time
+            if datetime_to_hamsterday(self.end_time) != datetime_to_hamsterday(self.start_time):
+                end_time_str = self.end_time.strftime(DATETIME_FMT)
+            else:
+                end_time_str = self.end_time.strftime(TIME_FMT)
+            time_str = "{} - {}".format(time_str, end_time_str)
+        return time_str
 
-    def serialized(self, prepend_date=True):
+    def serialized(self, default_day=None):
         """Return a string fully representing the fact."""
         name = self.serialized_name()
-        datetime = self.serialized_time(prepend_date)
+        datetime = self.serialized_range(default_day)
         # no need for space if name or datetime is missing
         space = " " if name and datetime else ""
         return "{}{}{}".format(datetime, space, name)
@@ -192,7 +204,7 @@ def __eq__(self, other):
                 )
 
     def __repr__(self):
-        return self.serialized(prepend_date=True)
+        return self.serialized(default_day=None)
 
 
 def default_logger(name):
diff --git a/src/hamster/lib/parsing.py b/src/hamster/lib/parsing.py
index 4c9f8b85e..23795d4de 100644
--- a/src/hamster/lib/parsing.py
+++ b/src/hamster/lib/parsing.py
@@ -17,6 +17,7 @@
 
 DATE_FMT = "%Y-%m-%d"  # ISO format
 TIME_FMT = "%H:%M"
+DATETIME_FMT = "{} {}".format(DATE_FMT, TIME_FMT)
 # separator between times and activity
 ACTIVITY_SEPARATOR = "\s+"
 
diff --git a/src/hamster/widgets/activityentry.py b/src/hamster/widgets/activityentry.py
index 398a54c08..953de72b0 100644
--- a/src/hamster/widgets/activityentry.py
+++ b/src/hamster/widgets/activityentry.py
@@ -415,7 +415,7 @@ def update_suggestions(self, text=""):
 
             if variant_fact:
                 variant_fact.description = None
-                variant = variant_fact.serialized(prepend_date=False)
+                variant = variant_fact.serialized(default_day=None)
                 variants.append((description, variant))
 
         else: