diff --git a/src/icn.jl b/src/icn.jl
index a0047eb..2c21632 100644
--- a/src/icn.jl
+++ b/src/icn.jl
@@ -133,6 +133,7 @@ function _compose(icn::ICN)
 
         if exclu(layer)
             f_id = as_int(@view weights(icn)[_start:_end])
+            # @warn "debug" f_id _end _start weights(icn) (exclu(layer) ? "nbits_exclu(layer)" : "length(layer)") (@view weights(icn)[_start:_end])
             s = symbol(layer, f_id + 1)
             push!(funcs, [functions(layer)[s]])
             push!(symbols, [s])
diff --git a/src/layer.jl b/src/layer.jl
index 53646f0..18be36f 100644
--- a/src/layer.jl
+++ b/src/layer.jl
@@ -30,7 +30,12 @@ exclu(layer) = layer.exclusive
     symbol(layer, i)
 Return the i-th symbols of the operations in a given layer.
 """
-symbol(layer, i) = collect(keys(functions(layer)))[i]
+symbol(layer, i) = begin
+    if i > length(layer)
+        @info layer i functions(layer)
+    end
+    collect(keys(functions(layer)))[i]
+end
 
 """
     nbits_exclu(layer)