diff --git a/engine/rowset/src/main/java/io/deephaven/engine/rowset/impl/singlerange/SingleRange.java b/engine/rowset/src/main/java/io/deephaven/engine/rowset/impl/singlerange/SingleRange.java
index 9302f51763f..b99bbefbe3c 100644
--- a/engine/rowset/src/main/java/io/deephaven/engine/rowset/impl/singlerange/SingleRange.java
+++ b/engine/rowset/src/main/java/io/deephaven/engine/rowset/impl/singlerange/SingleRange.java
@@ -204,6 +204,15 @@ public final OrderedLongSet ixRemove(final long key) {
         return OrderedLongSet.twoRanges(rangeStart(), key - 1, key + 1, rangeEnd());
     }
 
+    private static long addSaturated(final long x, final long y) {
+        // we know x >= 0, y >= 0.
+        final long res = x + y;
+        if (res < 0) {
+            return Long.MAX_VALUE;
+        }
+        return res;
+    }
+
     @Override
     public final OrderedLongSet ixSubindexByPosOnNew(final long startPos, final long endPosExclusive) {
         final long endPos = endPosExclusive - 1; // make inclusive.
@@ -219,8 +228,8 @@ public final OrderedLongSet ixSubindexByPosOnNew(final long startPos, final long
             return ixCowRef();
         }
         return make(
-                Math.max(rangeStart() + startPos, rangeStart()),
-                Math.min(rangeStart() + endPos, rangeEnd()));
+                rangeStart() + startPos, // cannot overflow given previous checks: startPos < cardinality
+                Math.min(addSaturated(rangeStart(), endPos), rangeEnd()));
     }
 
     @Override
diff --git a/engine/rowset/src/test/java/io/deephaven/engine/rowset/impl/SingleRangeTest.java b/engine/rowset/src/test/java/io/deephaven/engine/rowset/impl/SingleRangeTest.java
index 68e2950afc3..c171daac05a 100644
--- a/engine/rowset/src/test/java/io/deephaven/engine/rowset/impl/SingleRangeTest.java
+++ b/engine/rowset/src/test/java/io/deephaven/engine/rowset/impl/SingleRangeTest.java
@@ -462,4 +462,14 @@ public void testRowSequenceIteratorAdvanceRegression0() {
         assertTrue(valid);
         assertEquals(1000, rsIt.peekNextKey());
     }
+
+    @Test
+    public void testSaturation() {
+        final long first = 1073741821;
+        final long last = first + 6;
+        final SingleRange sr = SingleRange.make(first, last);
+        final OrderedLongSet res = sr.ixSubindexByPosOnNew(5, Long.MAX_VALUE);
+        assertEquals(last - 1, res.ixFirstKey());
+        assertEquals(last, res.ixLastKey());
+    }
 }