diff --git a/test/estimation.jl b/test/estimation.jl
index fad934b..4f18f93 100644
--- a/test/estimation.jl
+++ b/test/estimation.jl
@@ -3,6 +3,7 @@ using Distributions: Uniform, Normal
 using Statistics: mean
 using LinearAlgebra: norm
 using PERK: perk, GaussianKernel, EuclideanKernel, GaussianRFF
+using StableRNGs: StableRNG
 
 
 function test_perk_1()
@@ -21,7 +22,7 @@ function test_perk_1()
     xhat = perk(rng, y, T, xDists, noiseDist, signalModels, kernel, ρ)
 
     error_rel = abs(xhat - xtrue) / xtrue
-    return isapprox(error_rel, 0.042677934398487306, atol = 1e-7)
+    @test isapprox(error_rel, 0.042677934398487306, atol = 1e-7)
 
 end
 
@@ -47,7 +48,8 @@ function test_perk_2()
     end
 
     error_rel_avg = sum(error_rel) / length(error_rel)
-    return isapprox(error_rel_avg, 0.043934535569840415, atol = 1e-7)
+    ref = VERSION < v"1.11" ? 0.043934535569840415 : 0.04400107950561938
+    @test isapprox(error_rel_avg, ref, atol = 1e-7)
 
 end
 
@@ -70,7 +72,7 @@ function test_perk_3()
     xhat = perk(rng, y, T, xDists, noiseDist, signalModels, kernel, ρ)
 
     error_rel = abs(xhat[] - xtrue) / xtrue
-    return isapprox(error_rel, 0.07054474887124002, atol = 1e-7)
+    @test isapprox(error_rel, 0.07054474887124002, atol = 1e-7)
 
 end
 
@@ -96,7 +98,9 @@ function test_perk_4()
     end
 
     error_rel_avg = sum(error_rel) / length(error_rel)
-    return isapprox(error_rel_avg, 0.05827088471817421, atol = 1e-7)
+    ref = VERSION < v"1.11" ? 0.05827088471817421 : 0.05822451811335079
+
+    @test isapprox(error_rel_avg, ref, atol = 1e-7)
 
 end
 
@@ -120,7 +124,7 @@ function test_perk_5()
     xhat = perk(rng, y, ν, T, xDists, νDists, noiseDist, signalModels, kernel, ρ)
 
     error_rel = abs(xhat[] - xtrue) / xtrue
-    return isapprox(error_rel, 0.0057175117436099755, atol = 1e-7)
+    @test isapprox(error_rel, 0.0057175117436099755, atol = 1e-7)
 
 end
 
@@ -146,7 +150,7 @@ function test_perk_6()
         signalModels, kernel, ρ)
 
     error_rel = norm(xhat .- xtrue) / (sqrt(N) * xtrue)
-    return isapprox(error_rel, 0.0009325470666789215, atol = 1e-7)
+    @test isapprox(error_rel, 0.0009325470666789215, atol = 1e-7)
 
 end
 
@@ -168,7 +172,7 @@ function test_perk_7()
     xhat = perk(rng, y, ν, T, xDists, νDists, noiseDist, signalModels, kernel, ρ)
 
     error_rel = abs(xhat[] - xtrue) / xtrue
-    return isapprox(error_rel, 0.1083022379521612, atol = 1e-7)
+    @test isapprox(error_rel, 0.1083022379521612, atol = 1e-7)
 
 end
 
@@ -190,7 +194,7 @@ function test_perk_8()
     xhat = perk(rng, y, ν, T, xDists, νDists, noiseDist, signalModels, kernel, ρ)
 
     error_rel = abs(xhat[] - xtrue) / xtrue
-    return isapprox(error_rel, 0.1083022379521612, atol = 1e-7)
+    @test isapprox(error_rel, 0.1083022379521612, atol = 1e-7)
 
 end
 
@@ -210,7 +214,7 @@ function test_perk_9()
     xhat = perk(rng, y, T, xDists, noiseDist, signalModels, kernel, ρ)
 
     error_rel = abs(xhat[] - xtrue) / xtrue
-    return isapprox(error_rel, 0.09566274665119057, atol = 1e-6)
+    @test isapprox(error_rel, 0.09566274665119057, atol = 1e-6)
 
 end
 
@@ -233,7 +237,7 @@ function test_perk_10()
     xhat = perk(rng, y, ν, T, xDists, νDists, noiseDist, signalModels, kernel, ρ)
 
     error_rel = norm(xhat .- xtrue) / (sqrt(N) * xtrue)
-    return isapprox(error_rel, 0.060384227201893494, atol = 1e-7)
+    @test isapprox(error_rel, 0.060384227201893494, atol = 1e-7)
 
 end
 
@@ -256,7 +260,7 @@ function test_perk_11()
     xhat = perk(rng, y, ν, T, xDists, νDists, noiseDist, signalModels, kernel, ρ)
 
     error_rel = norm(xhat .- xtrue) / (sqrt(N) * xtrue)
-    return isapprox(error_rel, 0.060384227201893494, atol = 1e-7)
+    @test isapprox(error_rel, 0.060384227201893494, atol = 1e-7)
 
 end
 
@@ -279,24 +283,24 @@ function test_perk_12()
     xhat = perk(rng, y, ν, T, xDists, νDists, noiseDist, signalModels, kernel, ρ)
 
     error_rel = norm(xhat .- xtrue) / (sqrt(N) * xtrue)
-    return isapprox(error_rel, 0.06038422720189351, atol = 1e-7)
+    @test isapprox(error_rel, 0.06038422720189351, atol = 1e-7)
 
 end
 
 
 @testset "PERK" begin
 
-    @test test_perk_1()
-    @test test_perk_2()
-    @test test_perk_3()
-    @test test_perk_4()
-    @test test_perk_5()
-    @test test_perk_6()
-    @test test_perk_7()
-    @test test_perk_8()
-    @test test_perk_9()
-    @test test_perk_10()
-    @test test_perk_11()
-    @test test_perk_12()
+    test_perk_1()
+    test_perk_2()
+    test_perk_3()
+    test_perk_4()
+    test_perk_5()
+    test_perk_6()
+    test_perk_7()
+    test_perk_8()
+    test_perk_9()
+    test_perk_10()
+    test_perk_11()
+    test_perk_12()
 
 end