diff --git a/src/ColorVectorSpace.jl b/src/ColorVectorSpace.jl
index e5b640d..adb2fa0 100644
--- a/src/ColorVectorSpace.jl
+++ b/src/ColorVectorSpace.jl
@@ -205,7 +205,15 @@ copy(c::MathTypes) = c
 (-)(c::MathTypes) = mapc(-, c)
 (-)(c::MathTypes{Bool}) = c
 abs(c::MathTypes) = mapc(abs, c)
-norm(c::MathTypes, p::Real=2) = (cc = channels(c); norm(cc, p)/(p == 0 ? length(cc) : length(cc)^(1/p)))
+function norm(c::MathTypes, p::Real=2) # FIXME: make the return types consistent
+    cc = acc.(channels(c))
+    l = norm(cc, p)
+    c isa AbstractGray && return l / (p == 0 ? 1 : 1.0)
+    n = length(cc)
+    p == 2 && return l / sqrt(n)
+    p == 0 && return l / n # n::Int
+    l / n^(1/p)
+end
 (⊙)(a::C, b::C) where {C<:MathTypes} = _mapc(rettype(*, a, b), _mul, a, b)
 (⋅)(a::C, b::C) where {C<:MathTypes} = throw(MethodError(dot, (a, b)))
 (⊗)(a::C, b::C) where {C<:MathTypes} = throw(MethodError(tensor, (a, b)))
diff --git a/test/runtests.jl b/test/runtests.jl
index 6497176..a149f89 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -149,6 +149,7 @@ ColorTypes.comp2(c::RGBA32) = alpha(c)
         @test norm(cf) == norm(cf, 2) == norm(gray(cf))
         @test norm(cf, 1)   == norm(gray(cf), 1)
         @test norm(cf, Inf) == norm(gray(cf), Inf)
+        @test norm(Gray(0.004N0f8)) ≈ Float32(0.004N0f8) # issue #183
         @test @inferred(abs(cf)) === Gray(0.1f0)
         cu = Gray{N0f8}(0.1)
         @test @inferred(2*cu) === cu*2 === Gray(2*gray(cu))
@@ -443,6 +444,7 @@ ColorTypes.comp2(c::RGBA32) = alpha(c)
         @test abs2(cv) ≈ norm(cv)^2
         @test_throws MethodError sum(abs2, RGB(0.1,0.2,0.3))
         @test norm(RGB(0.1,0.2,0.3)) ≈ sqrt(0.14)/sqrt(3)
+        @test norm(RGB(0.004N0f8)) ≈ Float32(0.004N0f8) # issue #183
 
         acu = RGB{N0f8}[cu]
         acf = RGB{Float32}[cf]
@@ -812,8 +814,9 @@ ColorTypes.comp2(c::RGBA32) = alpha(c)
         x = 0.4
         g = Gray(x)
         c = RGB(g)
-        for p in (0, 1, 2, Inf)
+        @testset "$p-norm equivalence" for p in (0, 1, 2, Inf)
             @test norm(x, p) == norm(g, p) ≈ norm(c, p)
+            @test (p == 0 ? 1.0 : NaN) === norm(Gray(NaN), p) === norm(RGB(NaN), p)
         end
         @test dot(x, x) == dot(g, g) ≈ dot(c, c)
         @test abs2(x) ≈ abs2(g) ≈ abs2(c)