diff --git a/test/runtests.jl b/test/runtests.jl
index 7e0ebe4..b77719d 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -50,27 +50,48 @@ end
     end
 end
 
-# # test recurrence relations: Phys Rev E 57, 7274 (1998)
-# @threads for i = 1:N
-#     @testset "wigner3j: recurrence relations, thread $i" begin
-#         for k = 1:div(8,N)
-#             j2 = convert(BigFloat, rand(largejlist))
-#             j3 = convert(BigFloat, rand(largejlist))
-#             m2 = -convert(BigFloat, rand(-j2:0))
-#             m3 = convert(BigFloat, rand(-j3:0))
-#
-#             for j in max(abs(j2-j3),abs(m2+m3))+1:(j2+j3)-1
-#                 X = j*sqrt(((j+1)^2-(j2-j3)^2)*((j2+j3+1)^2-(j+1)^2)*((j+1)^2-(m2+m3)^2))
-#                 Y = (2*j+1)*((m2+m3)*(j2*(j2+1)-j3*(j3+1)) - (m2-m3)*j*(j+1))
-#                 Z = (j+1)*sqrt((j^2-(j2-j3)^2)*((j2+j3+1)^2-j^2)*(j^2-(m2+m3)^2))
-#                 tol = 10*max(abs(X),abs(Y),abs(Z))*eps(BigFloat)
-#                 @test (X*wigner3j(BigFloat,j+1,j2,j3,-m2-m3,m2,m3) +
-#                             Z*wigner3j(BigFloat,j-1,j2,j3,-m2-m3,m2,m3)) ≈
-#                                 (-Y*wigner3j(BigFloat,j,j2,j3,-m2-m3,m2,m3)) atol=tol
-#             end
-#         end
-#     end
-# end
+# test recurrence relations: Phys Rev E 57, 7274 (1998)
+if Base.Sys.iswindows() # not sure why the multithreaded version fails on Windows
+    @testset "wigner3j: recurrence relations" begin
+        for k = 1:8
+            j2 = convert(BigFloat, rand(largejlist))
+            j3 = convert(BigFloat, rand(largejlist))
+            m2 = -convert(BigFloat, rand(-j2:0))
+            m3 = convert(BigFloat, rand(-j3:0))
+
+            for j in max(abs(j2-j3),abs(m2+m3))+1:(j2+j3)-1
+                X = j*sqrt(((j+1)^2-(j2-j3)^2)*((j2+j3+1)^2-(j+1)^2)*((j+1)^2-(m2+m3)^2))
+                Y = (2*j+1)*((m2+m3)*(j2*(j2+1)-j3*(j3+1)) - (m2-m3)*j*(j+1))
+                Z = (j+1)*sqrt((j^2-(j2-j3)^2)*((j2+j3+1)^2-j^2)*(j^2-(m2+m3)^2))
+                tol = 10*max(abs(X),abs(Y),abs(Z))*eps(BigFloat)
+                @test (X*wigner3j(BigFloat,j+1,j2,j3,-m2-m3,m2,m3) +
+                            Z*wigner3j(BigFloat,j-1,j2,j3,-m2-m3,m2,m3)) ≈
+                                (-Y*wigner3j(BigFloat,j,j2,j3,-m2-m3,m2,m3)) atol=tol
+            end
+        end
+    end
+else
+    @threads for i = 1:N
+        @testset "wigner3j: recurrence relations, thread $i" begin
+            for k = 1:div(8,N)
+                j2 = convert(BigFloat, rand(largejlist))
+                j3 = convert(BigFloat, rand(largejlist))
+                m2 = -convert(BigFloat, rand(-j2:0))
+                m3 = convert(BigFloat, rand(-j3:0))
+
+                for j in max(abs(j2-j3),abs(m2+m3))+1:(j2+j3)-1
+                    X = j*sqrt(((j+1)^2-(j2-j3)^2)*((j2+j3+1)^2-(j+1)^2)*((j+1)^2-(m2+m3)^2))
+                    Y = (2*j+1)*((m2+m3)*(j2*(j2+1)-j3*(j3+1)) - (m2-m3)*j*(j+1))
+                    Z = (j+1)*sqrt((j^2-(j2-j3)^2)*((j2+j3+1)^2-j^2)*(j^2-(m2+m3)^2))
+                    tol = 10*max(abs(X),abs(Y),abs(Z))*eps(BigFloat)
+                    @test (X*wigner3j(BigFloat,j+1,j2,j3,-m2-m3,m2,m3) +
+                                Z*wigner3j(BigFloat,j-1,j2,j3,-m2-m3,m2,m3)) ≈
+                                    (-Y*wigner3j(BigFloat,j,j2,j3,-m2-m3,m2,m3)) atol=tol
+                end
+            end
+        end
+    end
+end
 
 @threads for i = 1:N
     @testset "wigner3j: orthogonality relations, thread $i" begin