diff -r d13adbcebf0c src/tests/unit/bitset.bitc
--- a/src/tests/unit/bitset.bitc	Tue Oct 19 14:34:41 2010 -0700
+++ b/src/tests/unit/bitset.bitc	Sun Oct 24 10:35:46 2010 -0700
@@ -76,4 +76,18 @@
       then stdio.write_string(stdio.stdout, "Contains 5 (and shouldn't)\n")
       else stdio.write_string(stdio.stdout, "!Contains 5 (and shouldn't)\n")
 
+    try bitset.insert(s, 31)
+    catch e
+      otherwise
+        stdio.write_string(stdio.stdout, "Insert failed on word boundry\n")
+        ()
+
+    if try bitset.contains(s, 31)
+      catch e
+        otherwise
+          stdio.write_string(stdio.stdout, "Contains failed on word boundry\n")
+          false 
+      then stdio.write_string(stdio.stdout, "Contains 31 (and should)\n")
+      else stdio.write_string(stdio.stdout, "!Contains 31 (and should)\n")
+
     0:int32