diff --git a/src/definitions.jl b/src/definitions.jl
index 5fd7e1e..41df3e5 100644
--- a/src/definitions.jl
+++ b/src/definitions.jl
@@ -345,12 +345,11 @@ plan_irfft
 ##############################################################################
 
 """
-	fftshift!(dest, src, [dim])
+    fftshift!(dest, src, [dim])
 
 Nonallocating version of [`fftshift`](@ref). Stores the result of the shift of the `src` array into the `dest` array.
 """
 function fftshift!(dest, src, dim = 1:ndims(src))
-	@assert size(dest)==size(src)
     s = ntuple(d -> d in dim ? div(size(dest,d),2) : 0, Val(ndims(dest)))
     circshift!(dest, src, s)
 end
@@ -372,18 +371,14 @@ The output of `fftshift` is allocated. If one desires to store the output in a p
 """
 fftshift
 
-function fftshift(x, dim = 1:ndims(x))
-	dest = similar(x)
-	fftshift!(dest, x, dim)
-end
+fftshift(x, dim = 1:ndims(x)) = fftshift!(similar(x), x, dim)
 
 """
-	ifftshift!(dest, src, [dim])
+    ifftshift!(dest, src, [dim])
 
 Nonallocating version of [`ifftshift`](@ref). Stores the result of the shift of the `src` array into the `dest` array.
 """
 function ifftshift!(dest, src, dim = 1:ndims(src))
-	@assert size(dest)==size(src)
     s = ntuple(d -> d in dim ? -div(size(src,d),2) : 0, Val(ndims(src)))
     circshift!(dest, src, s)
 end
@@ -405,10 +400,7 @@ The output of `ifftshift` is allocated. If one desires to store the output in a
 """
 ifftshift
 
-function ifftshift(x, dim = 1:ndims(x))
-	dest = similar(x)
-	ifftshift!(dest, x, dim)
-end
+ifftshift(x, dim = 1:ndims(x)) = ifftshift!(similar(x), x, dim)
 
 ##############################################################################
 
diff --git a/test/runtests.jl b/test/runtests.jl
index 869c745..95c7c5d 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -103,26 +103,26 @@ end
     @test @inferred(AbstractFFTs.fftshift([1 2 3])) == [3 1 2]
     @test @inferred(AbstractFFTs.fftshift([1, 2, 3])) == [3, 1, 2]
     @test @inferred(AbstractFFTs.fftshift([1 2 3; 4 5 6])) == [6 4 5; 3 1 2]
-	a = [0 0 0]
-	b = [0, 0, 0]
-	c = [0 0 0; 0 0 0]
-	@test (AbstractFFTs.fftshift!(a, [1 2 3]); a == [3 1 2])
-	@test (AbstractFFTs.fftshift!(b, [1, 2, 3]); b == [3, 1, 2])
+    a = [0 0 0]
+    b = [0, 0, 0]
+    c = [0 0 0; 0 0 0]
+    @test (AbstractFFTs.fftshift!(a, [1 2 3]); a == [3 1 2])
+    @test (AbstractFFTs.fftshift!(b, [1, 2, 3]); b == [3, 1, 2])
     @test (AbstractFFTs.fftshift!(c, [1 2 3; 4 5 6]); c == [6 4 5; 3 1 2])
 
     @test @inferred(AbstractFFTs.fftshift([1 2 3; 4 5 6], 1)) == [4 5 6; 1 2 3]
     @test @inferred(AbstractFFTs.fftshift([1 2 3; 4 5 6], ())) == [1 2 3; 4 5 6]
     @test @inferred(AbstractFFTs.fftshift([1 2 3; 4 5 6], (1,2))) == [6 4 5; 3 1 2]
     @test @inferred(AbstractFFTs.fftshift([1 2 3; 4 5 6], 1:2)) == [6 4 5; 3 1 2]
-	@test (AbstractFFTs.fftshift!(c, [1 2 3; 4 5 6], 1); c == [4 5 6; 1 2 3])
-	@test (AbstractFFTs.fftshift!(c, [1 2 3; 4 5 6], ()); c == [1 2 3; 4 5 6])
-	@test (AbstractFFTs.fftshift!(c, [1 2 3; 4 5 6], (1,2)); c == [6 4 5; 3 1 2])
-	@test (AbstractFFTs.fftshift!(c, [1 2 3; 4 5 6], 1:2); c == [6 4 5; 3 1 2])
+    @test (AbstractFFTs.fftshift!(c, [1 2 3; 4 5 6], 1); c == [4 5 6; 1 2 3])
+    @test (AbstractFFTs.fftshift!(c, [1 2 3; 4 5 6], ()); c == [1 2 3; 4 5 6])
+    @test (AbstractFFTs.fftshift!(c, [1 2 3; 4 5 6], (1,2)); c == [6 4 5; 3 1 2])
+    @test (AbstractFFTs.fftshift!(c, [1 2 3; 4 5 6], 1:2); c == [6 4 5; 3 1 2])
 
     @test @inferred(AbstractFFTs.ifftshift([1 2 3])) == [2 3 1]
     @test @inferred(AbstractFFTs.ifftshift([1, 2, 3])) == [2, 3, 1]
     @test @inferred(AbstractFFTs.ifftshift([1 2 3; 4 5 6])) == [5 6 4; 2 3 1]
-	@test (AbstractFFTs.ifftshift!(a, [1 2 3]); a == [2 3 1])
+    @test (AbstractFFTs.ifftshift!(a, [1 2 3]); a == [2 3 1])
     @test (AbstractFFTs.ifftshift!(b, [1, 2, 3]); b == [2, 3, 1])
     @test (AbstractFFTs.ifftshift!(c, [1 2 3; 4 5 6]); c == [5 6 4; 2 3 1])
 
@@ -130,10 +130,10 @@ end
     @test @inferred(AbstractFFTs.ifftshift([1 2 3; 4 5 6], ())) == [1 2 3; 4 5 6]
     @test @inferred(AbstractFFTs.ifftshift([1 2 3; 4 5 6], (1,2))) == [5 6 4; 2 3 1]
     @test @inferred(AbstractFFTs.ifftshift([1 2 3; 4 5 6], 1:2)) == [5 6 4; 2 3 1]
-	@test (AbstractFFTs.ifftshift!(c, [1 2 3; 4 5 6], 1); c == [4 5 6; 1 2 3])
-	@test (AbstractFFTs.ifftshift!(c, [1 2 3; 4 5 6], ()); c == [1 2 3; 4 5 6])
-	@test (AbstractFFTs.ifftshift!(c, [1 2 3; 4 5 6], (1,2)); c == [5 6 4; 2 3 1])
-	@test (AbstractFFTs.ifftshift!(c, [1 2 3; 4 5 6], 1:2); c == [5 6 4; 2 3 1])
+    @test (AbstractFFTs.ifftshift!(c, [1 2 3; 4 5 6], 1); c == [4 5 6; 1 2 3])
+    @test (AbstractFFTs.ifftshift!(c, [1 2 3; 4 5 6], ()); c == [1 2 3; 4 5 6])
+    @test (AbstractFFTs.ifftshift!(c, [1 2 3; 4 5 6], (1,2)); c == [5 6 4; 2 3 1])
+    @test (AbstractFFTs.ifftshift!(c, [1 2 3; 4 5 6], 1:2); c == [5 6 4; 2 3 1])
 end
 
 @testset "FFT Frequencies" begin