diff --git a/src/blenderbim/blenderbim/bim/module/sequence/prop.py b/src/blenderbim/blenderbim/bim/module/sequence/prop.py
index ef4eff3de4..28a77506b4 100644
--- a/src/blenderbim/blenderbim/bim/module/sequence/prop.py
+++ b/src/blenderbim/blenderbim/bim/module/sequence/prop.py
@@ -412,9 +412,9 @@ class BIMWorkScheduleProperties(PropertyGroup):
     visualisation_start: StringProperty(name="Visualisation Start", update=update_visualisation_start)
     visualisation_finish: StringProperty(name="Visualisation Finish", update=update_visualisation_finish)
     speed_multiplier: FloatProperty(name="Speed Multiplier", default=10000)
-    speed_animation_duration: StringProperty(name="Speed Animation Duration", default="PT1S")
+    speed_animation_duration: StringProperty(name="Speed Animation Duration", default="1 s")
     speed_animation_frames: IntProperty(name="Speed Animation Frames", default=24)
-    speed_real_duration: StringProperty(name="Speed Real Duration", default="P1W")
+    speed_real_duration: StringProperty(name="Speed Real Duration", default="1 w")
     speed_types: EnumProperty(
         items=[
             ("FRAME_SPEED", "Frame-based", "e.g. 25 frames = 1 real week"),
diff --git a/src/blenderbim/blenderbim/tool/sequence.py b/src/blenderbim/blenderbim/tool/sequence.py
index 39fc55cc99..157f2a6df7 100644
--- a/src/blenderbim/blenderbim/tool/sequence.py
+++ b/src/blenderbim/blenderbim/tool/sequence.py
@@ -1226,21 +1226,23 @@ class Sequence(blenderbim.core.tool.Sequence):
                     start,
                     finish,
                     props.speed_animation_frames,
-                    isodate.parse_duration(props.speed_real_duration),
+                    ifcopenshell.util.date.parse_duration(props.speed_real_duration)
                 )
             elif props.speed_types == "DURATION_SPEED":
+                animation_duration = ifcopenshell.util.date.parse_duration(props.speed_animation_duration)
+                real_duration = ifcopenshell.util.date.parse_duration(props.speed_real_duration)
                 return calculate_using_duration(
                     start,
                     finish,
                     fps,
-                    isodate.parse_duration(props.speed_animation_duration),
-                    isodate.parse_duration(props.speed_real_duration),
+                    animation_duration,
+                    real_duration,
                 )
             elif props.speed_types == "MULTIPLIER_SPEED":
                 return calculate_using_multiplier(
                     start,
                     finish,
-                    fps,
+                    1,
                     props.speed_multiplier,
                 )
 
diff --git a/src/blenderbim/test/bim/feature/sequence.feature b/src/blenderbim/test/bim/feature/sequence.feature
index 1015ef660e..81e40d63fd 100644
--- a/src/blenderbim/test/bim/feature/sequence.feature
+++ b/src/blenderbim/test/bim/feature/sequence.feature
@@ -326,7 +326,7 @@ Scenario: See the current frame date as text
     And I set "scene.BIMWorkScheduleProperties.visualisation_finish" to "01/02/21"
     And I set "scene.BIMWorkScheduleProperties.speed_types" to "FRAME_SPEED"
     And I set "scene.BIMWorkScheduleProperties.speed_animation_frames" to "7"
-    And I set "scene.BIMWorkScheduleProperties.speed_real_duration" to "P1W"
+    And I set "scene.BIMWorkScheduleProperties.speed_real_duration" to "1 w"
     And I press "bim.visualise_work_schedule_date_range(work_schedule={work_schedule})"
     When I am on frame "1"
     Then the object "Timeline" has a body of "2021-01-01"
@@ -357,7 +357,7 @@ Scenario: Animate the construction of a wall
     And I set "scene.BIMWorkScheduleProperties.visualisation_finish" to "01/02/21"
     And I set "scene.BIMWorkScheduleProperties.speed_types" to "FRAME_SPEED"
     And I set "scene.BIMWorkScheduleProperties.speed_animation_frames" to "7"
-    And I set "scene.BIMWorkScheduleProperties.speed_real_duration" to "P1W"
+    And I set "scene.BIMWorkScheduleProperties.speed_real_duration" to "1 w"
     And I press "bim.visualise_work_schedule_date_range(work_schedule={work_schedule})"
     When I am on frame "1"
     Then "scene.objects.get('IfcWall/Cube').hide_viewport" is "True"
@@ -393,7 +393,7 @@ Scenario: Animate the demolition of a wall
     And I set "scene.BIMWorkScheduleProperties.visualisation_finish" to "01/02/21"
     And I set "scene.BIMWorkScheduleProperties.speed_types" to "FRAME_SPEED"
     And I set "scene.BIMWorkScheduleProperties.speed_animation_frames" to "7"
-    And I set "scene.BIMWorkScheduleProperties.speed_real_duration" to "P1W"
+    And I set "scene.BIMWorkScheduleProperties.speed_real_duration" to "1 w"
     And I press "bim.visualise_work_schedule_date_range(work_schedule={work_schedule})"
     When I am on frame "1"
     Then "scene.objects.get('IfcWall/Cube').hide_viewport" is "False"
@@ -432,7 +432,7 @@ Scenario: Animate the operation of a wall
     And I set "scene.BIMWorkScheduleProperties.visualisation_finish" to "01/02/21"
     And I set "scene.BIMWorkScheduleProperties.speed_types" to "FRAME_SPEED"
     And I set "scene.BIMWorkScheduleProperties.speed_animation_frames" to "7"
-    And I set "scene.BIMWorkScheduleProperties.speed_real_duration" to "P1W"
+    And I set "scene.BIMWorkScheduleProperties.speed_real_duration" to "1 w"
     And I press "bim.visualise_work_schedule_date_range(work_schedule={work_schedule})"
     When I am on frame "1"
     Then "scene.objects.get('IfcWall/Cube').color[:]" is "[1.0, 1.0, 1.0, 1]"
@@ -472,7 +472,7 @@ Scenario: Animate the movement of a wall
     And I set "scene.BIMWorkScheduleProperties.visualisation_finish" to "01/02/21"
     And I set "scene.BIMWorkScheduleProperties.speed_types" to "FRAME_SPEED"
     And I set "scene.BIMWorkScheduleProperties.speed_animation_frames" to "7"
-    And I set "scene.BIMWorkScheduleProperties.speed_real_duration" to "P1W"
+    And I set "scene.BIMWorkScheduleProperties.speed_real_duration" to "1 w"
     And I press "bim.visualise_work_schedule_date_range(work_schedule={work_schedule})"
     When I am on frame "1"
     Then "scene.objects.get('IfcWall/FromObject').color[:]" is "[1.0, 1.0, 1.0, 1]"
@@ -516,7 +516,7 @@ Scenario: Animate the consumption of a wall
     And I set "scene.BIMWorkScheduleProperties.visualisation_finish" to "01/02/21"
     And I set "scene.BIMWorkScheduleProperties.speed_types" to "FRAME_SPEED"
     And I set "scene.BIMWorkScheduleProperties.speed_animation_frames" to "7"
-    And I set "scene.BIMWorkScheduleProperties.speed_real_duration" to "P1W"
+    And I set "scene.BIMWorkScheduleProperties.speed_real_duration" to "1 w"
     And I press "bim.visualise_work_schedule_date_range(work_schedule={work_schedule})"
     When I am on frame "1"
     Then "scene.objects.get('IfcWall/Cube').color[:]" is "[1.0, 1.0, 1.0, 1]"