diff --git a/lib/cldr/interval.ex b/lib/cldr/interval.ex
index 5aa5293..f9f9325 100644
--- a/lib/cldr/interval.ex
+++ b/lib/cldr/interval.ex
@@ -443,6 +443,13 @@ defmodule Cldr.Interval do
       to = %{to | second: 0, microsecond: {0, 6}}
       Cldr.DateTime.Interval.to_string(from, to, backend, options)
     end
+
+    def to_string(%CalendarInterval{first: from, last: to, precision: precision}, backend, options)
+        when precision in [:second, :microsecond] do
+      from = %{from | microsecond: {0, 6}}
+      to = %{to | microsecond: {0, 6}}
+      Cldr.DateTime.Interval.to_string(from, to, backend, options)
+    end
   end
 
   @doc false
diff --git a/lib/cldr/interval/date_time.ex b/lib/cldr/interval/date_time.ex
index 096ab40..19f4380 100644
--- a/lib/cldr/interval/date_time.ex
+++ b/lib/cldr/interval/date_time.ex
@@ -106,7 +106,7 @@ defmodule Cldr.DateTime.Interval do
     end
 
     def to_string(%CalendarInterval{first: from, last: to, precision: precision}, backend, options)
-        when precision in [:hour, :minute] do
+        when precision in [:hour, :minute, :second] do
       to_string(from, to, backend, options)
     end
   end
@@ -324,7 +324,7 @@ defmodule Cldr.DateTime.Interval do
     end
 
     def to_string!(%CalendarInterval{first: from, last: to, precision: precision}, backend, options)
-        when precision in [:hour, :minute] do
+        when precision in [:hour, :minute, :second] do
       to_string!(from, to, backend, options)
     end
   end