diff --git a/isthmus/src/main/java/io/substrait/isthmus/SubstraitTypeSystem.java b/isthmus/src/main/java/io/substrait/isthmus/SubstraitTypeSystem.java
index 849be1526..86d64f589 100644
--- a/isthmus/src/main/java/io/substrait/isthmus/SubstraitTypeSystem.java
+++ b/isthmus/src/main/java/io/substrait/isthmus/SubstraitTypeSystem.java
@@ -110,7 +110,6 @@ public int getMaxPrecision(final SqlTypeName typeName) {
       case INTERVAL_YEAR:
       case INTERVAL_YEAR_MONTH:
       case TIME:
-      case TIME_WITH_LOCAL_TIME_ZONE:
       case TIMESTAMP:
       case TIMESTAMP_WITH_LOCAL_TIME_ZONE:
         return 6;
diff --git a/isthmus/src/test/java/io/substrait/isthmus/SubstraitTypeSystemTest.java b/isthmus/src/test/java/io/substrait/isthmus/SubstraitTypeSystemTest.java
index 03dd4c77f..78730badf 100644
--- a/isthmus/src/test/java/io/substrait/isthmus/SubstraitTypeSystemTest.java
+++ b/isthmus/src/test/java/io/substrait/isthmus/SubstraitTypeSystemTest.java
@@ -161,6 +161,20 @@ void aRaggedBinaryUnionKeepsTheWidestWidth() {
     assertEquals(100_000, unified.getPrecision());
   }
 
+  @Test
+  void timeWithLocalTimeZoneHasNoSubstraitMaxPrecision() {
+    // Substrait has precision_timestamp_tz but no time-with-timezone counterpart, so this type
+    // converts in neither direction and there is no Substrait maximum to report for it.
+    assertThrows(
+        UnsupportedOperationException.class,
+        () ->
+            TypeConverter.DEFAULT.toSubstrait(
+                TYPE_FACTORY.createSqlType(SqlTypeName.TIME_WITH_LOCAL_TIME_ZONE, 3)));
+    assertEquals(
+        RelDataTypeSystem.DEFAULT.getMaxPrecision(SqlTypeName.TIME_WITH_LOCAL_TIME_ZONE),
+        typeSystem.getMaxPrecision(SqlTypeName.TIME_WITH_LOCAL_TIME_ZONE));
+  }
+
   @Test
   void canCreateDecimalWithMaxPrecision() {
     RelDataType decimalType = TYPE_FACTORY.createSqlType(SqlTypeName.DECIMAL, 38, 10);