diff --git a/esmvalcore/cmor/_fixes/cmip6/awi_esm_1_1_lr.py b/esmvalcore/cmor/_fixes/cmip6/awi_esm_1_1_lr.py
index 2c53d38fb4..13ac0ffd23 100644
--- a/esmvalcore/cmor/_fixes/cmip6/awi_esm_1_1_lr.py
+++ b/esmvalcore/cmor/_fixes/cmip6/awi_esm_1_1_lr.py
@@ -21,9 +21,10 @@ def fix_metadata(self, cubes):
         bad_value = 'days since 0000-01-01 00:00:00'
         for cube in cubes:
             try:
-                if cube.attributes[parent_units] == bad_value:
-                    cube.attributes[parent_units] = 'days since 0001-01-01 ' \
-                        + '00:00:00'
+                if parent_units in cube.attributes:
+                    if cube.attributes[parent_units] == bad_value:
+                        cube.attributes[parent_units] = \
+                            'days since 0001-01-01 00:00:00'
             except AttributeError:
                 pass
         return cubes