diff --git a/src/FixedPointNumbers.jl b/src/FixedPointNumbers.jl
index 0e394c0..35284cc 100644
--- a/src/FixedPointNumbers.jl
+++ b/src/FixedPointNumbers.jl
@@ -6,7 +6,7 @@ import Base: ==, <, <=, -, +, *, /, ~, isapprox,
              zero, oneunit, one, typemin, typemax, floatmin, floatmax, eps, reinterpret,
              big, rationalize, float, trunc, round, floor, ceil, bswap, clamp,
              div, fld, cld, rem, mod, mod1, fld1, min, max, minmax,
-             signed, unsigned, copysign, flipsign, signbit,
+             copysign, flipsign, signbit,
              length, widen, widemul
 
 import Random: Random, AbstractRNG, SamplerType, rand!
@@ -362,14 +362,6 @@ clamp(x::X, lo::X, hi::X) where {X <: FixedPoint} = X(clamp(x.i, lo.i, hi.i), 0)
 
 clamp(x, ::Type{X}) where {X <: FixedPoint} = clamp(x, typemin(X), typemax(X)) % X
 
-# Since `FixedPoint` is not an integer type, it is not clear in what type
-# `signed` and `unsigned` for `FixedPoint` should return values. They should
-# currently throw errors in case we support "unsigned Fixed" or "signed Normed"
-# in the future. The following "incomplete" code is necessary for Julia v1.0
-# etc. to prevent accidental conversion to an integer type.
-signed(x::X) where {X <: FixedPoint} = signed(X)(signed(x.i), 0)
-unsigned(x::X) where {X <: FixedPoint} = unsigned(X)(unsigned(x.i), 0)
-
 function copysign(x::X, y::Real) where {T, X <: FixedPoint{T}}
     T <: Signed ? X(copysign(x.i, y), 0) : throw_not_a_signed_number_error(x)
 end
diff --git a/test/common.jl b/test/common.jl
index 3a04608..5f02a01 100644
--- a/test/common.jl
+++ b/test/common.jl
@@ -375,6 +375,20 @@ function test_clamp_nan(TX::Type)
     end
 end
 
+function test_sign_related(TX::Type)
+    for X in target(TX, :i8; ex = :thin)
+        if VERSION >= v"1.4"
+            # `FixedPoint` is not a signed or unsigned integer type
+            @test_throws Exception signed(X)
+            @test_throws Exception signed(X(0.5))
+            @test_throws Exception unsigned(X)
+            @test_throws Exception unsigned(X(0.5))
+        end
+
+        @test signbit(X(0.5)) === signbit(X(0.0)) === false
+    end
+end
+
 function test_isinteger(TX::Type)
     @testset "isinteger(::$X)" for X in target(TX, :i8, :i16)
         xs = typemin(X):eps(X):typemax(X)
diff --git a/test/fixed.jl b/test/fixed.jl
index bcfce6d..baa4c3a 100644
--- a/test/fixed.jl
+++ b/test/fixed.jl
@@ -614,19 +614,17 @@ end
 end
 
 @testset "sign-related functions" begin
-    @test_throws Exception signed(Q0f7)
-    @test_throws Exception signed(0.5Q0f7)
-    @test_throws Exception unsigned(Q0f7)
-    @test_throws Exception unsigned(0.5Q0f7)
+    test_sign_related(Fixed)
+
     @test copysign(0.5Q0f7, 0x1) === 0.5Q0f7
     @test copysign(0.5Q0f7, -1) === -0.5Q0f7
     @test flipsign(0.5Q0f7, 0x1) === 0.5Q0f7
     @test flipsign(0.5Q0f7, -1) === -0.5Q0f7
-    @test_throws ArgumentError sign(0Q0f7)
+    @test_broken sign(0Q0f7) === zero(Q0f7)
+    @test_throws ArgumentError sign(0.5Q0f7)
     @test sign(0Q1f6) === 0Q1f6
     @test sign(0.5Q1f6) === 1Q1f6
     @test sign(-0.5Q1f6) === -1Q1f6
-    @test signbit(0.5Q0f7) === false
     @test signbit(-0.5Q0f7) === true
 end
 
diff --git a/test/normed.jl b/test/normed.jl
index 03f73fa..8c1010a 100644
--- a/test/normed.jl
+++ b/test/normed.jl
@@ -596,16 +596,14 @@ end
 end
 
 @testset "sign-related functions" begin
-    @test_throws Exception signed(N0f8)
-    @test_throws Exception signed(1N0f8)
-    @test_throws Exception unsigned(N0f8)
-    @test_throws Exception unsigned(1N0f8)
+    test_sign_related(Normed)
+
     @test_throws ArgumentError copysign(1N0f8, 0x1)
     @test_throws ArgumentError copysign(1N0f8, -1)
     @test_throws ArgumentError flipsign(1N0f8, 0x1)
     @test_throws ArgumentError flipsign(1N0f8, -1)
-    @test_throws ArgumentError sign(0N0f8)
-    @test signbit(1N0f8) === false
+    @test_broken sign(0N0f8) === zero(N0f8)
+    @test_broken sign(0.5N0f8) === oneunit(N0f8)
 end
 
 @testset "bitwise" begin