diff --git a/src/Blocks/continuous.jl b/src/Blocks/continuous.jl
index f7c2116b..0d856cab 100644
--- a/src/Blocks/continuous.jl
+++ b/src/Blocks/continuous.jl
@@ -116,9 +116,9 @@ sT + 1
 and if `lowpass=false`, by
 
 ```
-sT + 1 - k
-──────────
-  sT + 1
+ k*sT
+───────
+sT + 1
 ```
 
 Initial value of the state `x` can be set with `x`
diff --git a/test/continuous.jl b/test/continuous.jl
index 40c1289d..e1ad8b7e 100644
--- a/test/continuous.jl
+++ b/test/continuous.jl
@@ -57,14 +57,20 @@ end
     @test sol.retcode == Success
     @test sol[pt1.output.u] ≈ pt1_func.(sol.t, k, T) atol = 1.0e-3
 
-    # Test highpass feature
+    # Highpass: Y/U = k*sT/(sT+1); unit-step response y(t) = k*exp(-t/T)
+    highpass_step(t, k, T) = k * exp(-t / T)
+    abstol = 1.0e-6
+    reltol = 1.0e-6
     @named pt1 = FirstOrder(; k = k, T = T, lowpass = false)
     @named iosys = System(connect(c.output, pt1.input), t, systems = [pt1, c])
     sys = mtkcompile(iosys)
     prob = ODEProblem(sys, Pair[], (0.0, 100.0))
-    sol = solve(prob, Rodas4())
+    sol = solve(prob, Rodas4(); abstol, reltol)
     @test sol.retcode == Success
-    @test sol[pt1.output.u] ≈ k .- pt1_func.(sol.t, k, T) atol = 1.0e-3
+    # 100× margin over solver tolerances (scaled by gain magnitude)
+    tol = 100 * max(abstol, reltol * abs(k))
+    @test sol[pt1.output.u] ≈ highpass_step.(sol.t, k, T) atol = tol
+    @test abs(sol[pt1.output.u][end]) ≤ tol # asymptotic DC gain is 0
 end
 
 @testset "PT2" begin