diff --git a/src/macro.jl b/src/macro.jl
index 98005cb..e149965 100644
--- a/src/macro.jl
+++ b/src/macro.jl
@@ -958,14 +958,21 @@ function make_many_actors(act!, args, ex1, outer::Vector, ex3, inner::Vector, ex
                 outer = [Symbol(EPS, 1)] # fake index name, only appears in @index
                 sizes = [:(one(Int))]    # iterate over 1:1
             end
-            kex1 = macroexpand(store.mod, quote
+            ka_args = map(args) do x # mark everything const, except for ZED::AbstractArray{TYP} and gradients
+                x isa Symbol || return x
+                startswith(string(x), string(DEL)) && x != Symbol(DEL, ZED) && return x
+                :(@Const($x))
+            end
+            kex0 = quote
 
-                KernelAbstractions.@kernel function $kernel($(args...), $KEEP, $FINAL) where {$TYP}
+                KernelAbstractions.@kernel function $kernel($(ka_args...), @Const($KEEP), @Const($FINAL)) where {$TYP}
                     ($(outer...),) = @index(Global, NTuple)
-                    ($ex1; $ex3; $ex4; $ex6)
+                    @views ($ex1; $ex3; $ex4; $ex6)
                 end
 
-            end)
+            end
+            store.verbose==2 && @show verbosetidy(kex0)
+            kex1 = macroexpand(store.mod, kex0)
             push!(store.outpre, kex1)
             if isdefined(store.mod, :CUDA) && isdefined(store.mod, :CuArray) # new-style, CUDA.jl, with CUDADevice()
                 info2 = store.verbose>0 ? :(@info "running KernelAbstractions + CUDA actor $($note)") : nothing
diff --git a/test/parsing.jl b/test/parsing.jl
index 7b8dce6..83c18d7 100644
--- a/test/parsing.jl
+++ b/test/parsing.jl
@@ -135,6 +135,12 @@ using Tullio, Test, LinearAlgebra
     @test A == @tullio P[i'] := A[i′]
     @test [1,4,9] == @tullio Q[i'] := (i′)^2  (i' in 1:3)
 
+    # colons
+    @tullio R[i] := prod(M[:,i]) avx=false
+    @test R ≈ vec(prod(M, dims=1))
+
+    # @tullio S[:,i] := cumsum(M[:,i]) avx=false
+
     # non-numeric array
     @tullio Y[i] := (ind=i, val=A[i])
     @test Y[2] === (ind = 2, val = 4)
@@ -205,6 +211,15 @@ end
 
     @test_throws LoadError @eval @tullio [i,j] = A[i] + 100
 
+    # colons
+    R = similar(A)
+    @tullio R[i] = sum(D[:,i]) avx=false
+    @test R == vec(sum(D, dims=1))
+
+    S = similar(D);
+    @tullio S[i,:] = cumsum(D[:,i]) avx=false
+    @test_broken S == cumsum(D, dims=1)
+
     # zero off-diagonal? not now, but maybe it should?
     @tullio D[i,i] = A[i]