diff --git a/dbt/include/spark/macros/utils/datediff.sql b/dbt/include/spark/macros/utils/datediff.sql
index d0e684c47..5eeb0281a 100644
--- a/dbt/include/spark/macros/utils/datediff.sql
+++ b/dbt/include/spark/macros/utils/datediff.sql
@@ -73,12 +73,12 @@
         {%- endset -%}
 
         case when {{first_date}} < {{second_date}}
-            then ceil((
+            then floor((
                 {# make sure the timestamps are real, otherwise raise an error asap #}
                 {{ assert_not_null('to_unix_timestamp', assert_not_null('to_timestamp', second_date)) }}
                 - {{ assert_not_null('to_unix_timestamp', assert_not_null('to_timestamp', first_date)) }}
             ) / {{divisor}})
-            else floor((
+            else ceil((
                 {{ assert_not_null('to_unix_timestamp', assert_not_null('to_timestamp', second_date)) }}
                 - {{ assert_not_null('to_unix_timestamp', assert_not_null('to_timestamp', first_date)) }}
             ) / {{divisor}})
@@ -105,3 +105,4 @@
     {%- endif -%}
 
 {% endmacro %}
+