diff --git a/test/runtests.jl b/test/runtests.jl
index bb3027e..0ed1504 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -238,10 +238,12 @@ end
             for dims in unique((1, 1:N, N))
                 P = plan_fft(x, dims)
                 @test (P')' * x == P * x # test adjoint of adjoint
-                @test dot(y, P * x) ≈ dot(P' * y, x)
+                @test size(P') == AbstractFFTs.output_size(P) # test size of adjoint 
+                @test dot(y, P * x) ≈ dot(P' * y, x) # test validity of adjoint
                 @test_broken dot(y, P \ x) ≈ dot(P' \ y, x)
                 Pinv = plan_ifft(y)
-                @test (Pinv')' * y == Pinv * y # test adjoint of adjoint
+                @test (Pinv')' * y == Pinv * y 
+                @test size(Pinv') == AbstractFFTs.output_size(Pinv) 
                 @test dot(x, Pinv * y) ≈ dot(Pinv' * x, y)
                 @test_broken dot(x, Pinv \ y) ≈ dot(Pinv' \ x, y)
             end
@@ -252,14 +254,16 @@ end
             N = ndims(x)
             for dims in unique((1, 1:N, N))
                 P = plan_rfft(x, dims)        
-                @test (P')' * x == P * x
                 y_real = randn(size(P * x))
                 y_imag = randn(size(P * x))
                 y = y_real .+ y_imag .* im 
+                @test (P')' * x == P * x
+                @test size(P') == AbstractFFTs.output_size(P) 
                 @test dot(y_real, real.(P * x)) + dot(y_imag, imag.(P * x)) ≈ dot(P' * y, x)
                 @test_broken dot(y_real, real.(P \ x)) + dot(y_imag, imag.(P \ x)) ≈ dot(P' * y, x)
                 Pinv = plan_irfft(y, size(x)[first(dims)], dims)
                 @test (Pinv')' * y == Pinv * y
+                @test size(Pinv') == AbstractFFTs.output_size(Pinv) 
                 @test dot(x, Pinv * y) ≈ dot(y_real, real.(Pinv' * x)) + dot(y_imag, imag.(Pinv' * x))
                 @test_broken dot(x, Pinv \ y) ≈ dot(y_real, real.(Pinv' \ x)) + dot(y_imag, imag.(Pinv' \ x))
             end