diff --git a/src/index.jl b/src/index.jl
index 99ce8ff75a..795cb147e1 100644
--- a/src/index.jl
+++ b/src/index.jl
@@ -34,11 +34,8 @@ associated with an index, i.e. the index leg is directed into or out of a given
 Reverse direction of a directed `Arrow`. Will throw an error for an input of `Neither`.
 """
 function -(dir::Arrow)
-  if dir==Neither
-    error("Cannot reverse direction of Arrow direction 'Neither'")
-  else
-    return dir==In ? Out : In
-  end
+  dir==Neither && throw(ArgumentError("Cannot reverse direction of Arrow direction 'Neither'"))
+  return dir==In ? Out : In
 end
 
 """
diff --git a/test/test_index.jl b/test/test_index.jl
index 336f31c26b..be72acbaa8 100644
--- a/test/test_index.jl
+++ b/test/test_index.jl
@@ -9,6 +9,7 @@ import ITensors: In,Out,Neither
     @test id(i) == 0
     @test dim(i) == 1
     @test dir(i) == Neither
+    @test_throws ArgumentError -dir(i)
     @test plev(i) == 0
     @test tags(i) == TagSet("0")
   end
@@ -46,6 +47,8 @@ import ITensors: In,Out,Neither
     @test plev(i2) == 2
     i3 = i'''
     @test plev(i3) == 3
+    i0 = noprime(i)
+    @test plev(i0) == 0
   end
   @testset "IndexVal" begin
     i = Index(2)
@@ -59,5 +62,7 @@ import ITensors: In,Out,Neither
     @test plev(i(2)') == 1
     @test val(i(2)') == 2
     @test plev(prime(i(2),4)) == 4
+    @test i[:] == [i(1); i(2)]
+    @test sprint(show, i(2)) == sprint(show, i)*"=2"
   end
 end