diff --git a/Project.toml b/Project.toml
index 1395ead..ddec63f 100644
--- a/Project.toml
+++ b/Project.toml
@@ -10,6 +10,7 @@ DocStringExtensions = "ffbed154-4ef7-542d-bbb7-c09d3a79fcae"
 Flux = "587475ba-b771-5e3f-ad9e-33799f191a9c"
 Functors = "d9f16b24-f501-4c13-a1f2-28368ffc5196"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
+NNlib = "872c559c-99b0-510c-b3b7-b6c96a88d5cd"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 Reexport = "189a3867-3050-52da-a836-e630ba90ab69"
 SciMLBase = "0bca4576-84f4-4d90-8ffe-ffa030f20462"
@@ -31,6 +32,7 @@ DocStringExtensions = "0.9.3"
 Flux = "0.14.16, 0.15, 0.16"
 Functors = "0.4.11, 0.5"
 LinearAlgebra = "1.10"
+NNlib = "0.9"
 Random = "1.10"
 Reexport = "1.2.2"
 SafeTestsets = "0.1"
diff --git a/src/HighDimPDE.jl b/src/HighDimPDE.jl
index 332ac77..139f69d 100644
--- a/src/HighDimPDE.jl
+++ b/src/HighDimPDE.jl
@@ -16,6 +16,17 @@ using Tracker
 using CUDA, cuDNN
 using Random
 using SparseArrays
+using NNlib
+
+# Disable NNlib's `tanh_fast` substitution on CuArrays. Inside
+# `NNlib.bias_act!`, the activation is wrapped into a `ComposedFunction
+# (σ, +)` that is broadcast on GPU. With the polynomial `tanh_fast`,
+# GPU compilation of the resulting `Broadcasted{ComposedFunction{...}}`
+# kernel hits an unsupported dynamic dispatch through the
+# `ComposedFunction` kwsorter, while the device intrinsic `tanh`
+# compiles cleanly. Same fix as suggested for Metal in
+# https://github.com/FluxML/Flux.jl/issues/2633.
+NNlib.fast_act(::typeof(tanh), ::CuArray) = tanh
 
 abstract type HighDimPDEAlgorithm <: DiffEqBase.AbstractODEAlgorithm end
 abstract type AbstractPDEProblem <: SciMLBase.AbstractSciMLProblem end
diff --git a/test/qa.jl b/test/qa.jl
index 4ab460f..e8cb757 100644
--- a/test/qa.jl
+++ b/test/qa.jl
@@ -1,9 +1,15 @@
 using HighDimPDE, Aqua
+using NNlib: NNlib
 @testset "Aqua" begin
     Aqua.find_persistent_tasks_deps(HighDimPDE)
     Aqua.test_ambiguities(HighDimPDE, recursive = false)
     Aqua.test_deps_compat(HighDimPDE)
-    Aqua.test_piracies(HighDimPDE)
+    # `NNlib.fast_act(::typeof(tanh), ::CuArray) = tanh` is intentional
+    # type piracy: a CUDA-side opt-out of NNlib's `tanh_fast` substitution
+    # that works around an `InvalidIRError` when broadcasting
+    # `ComposedFunction{tanh_fast, +}` on the GPU. See FluxML/Flux.jl#2633
+    # for the analogous Metal report and resolution.
+    Aqua.test_piracies(HighDimPDE, treat_as_own = [NNlib.fast_act])
     Aqua.test_project_extras(HighDimPDE)
     Aqua.test_stale_deps(HighDimPDE)
     Aqua.test_unbound_args(HighDimPDE)