diff --git a/Project.toml b/Project.toml
index f35b1df4..41e11f26 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,6 +1,6 @@
 name = "AdvancedHMC"
 uuid = "0bf59076-c3b1-5ca4-86bd-e02cd72cde3d"
-version = "0.6.3"
+version = "0.6.4"
 
 [deps]
 AbstractMCMC = "80f14c24-f653-4e6a-9b94-39d6b0f70001"
diff --git a/src/hamiltonian.jl b/src/hamiltonian.jl
index b5546051..f8f2ab32 100644
--- a/src/hamiltonian.jl
+++ b/src/hamiltonian.jl
@@ -108,6 +108,10 @@ Base.isfinite(v::DualValue) = all(isfinite, v.value) && all(isfinite, v.gradient
 Base.isfinite(v::AbstractVecOrMat) = all(isfinite, v)
 Base.isfinite(z::PhasePoint) = isfinite(z.ℓπ) && isfinite(z.ℓκ)
 
+Base.isnan(v::DualValue) = any(isnan, v.value) || any(isnan, v.gradient)
+Base.isnan(v::AbstractVecOrMat) = any(isnan, v)
+Base.isnan(z::PhasePoint) = isnan(z.ℓπ) || isnan(z.ℓκ)
+
 ###
 ### Negative energy (or log probability) functions.
 ### NOTE: the general form (i.e. non-Euclidean) of K depends on both θ and r.