diff --git a/Project.toml b/Project.toml
index 4e4eb4cac..3251939c3 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,6 +1,6 @@
 name = "DynamicPPL"
 uuid = "366bfd00-2699-11ea-058f-f148b4cae6d8"
-version = "0.23.5"
+version = "0.23.6"
 
 [deps]
 AbstractMCMC = "80f14c24-f653-4e6a-9b94-39d6b0f70001"
diff --git a/src/test_utils.jl b/src/test_utils.jl
index cc2d27803..394341c04 100644
--- a/src/test_utils.jl
+++ b/src/test_utils.jl
@@ -621,6 +621,13 @@ const UnivariateAssumeDemoModels = Union{
 function posterior_mean(model::UnivariateAssumeDemoModels)
     return (s=49 / 24, m=7 / 6)
 end
+function likelihood_optima(::DynamicPPL.TestUtils.UnivariateAssumeDemoModels)
+    return (s=1 / 16, m=7 / 4)
+end
+function posterior_optima(::DynamicPPL.TestUtils.UnivariateAssumeDemoModels)
+    # TODO: Figure out exact for `s`.
+    return (s=0.907407, m=7 / 6)
+end
 function Random.rand(
     rng::Random.AbstractRNG, ::Type{NamedTuple}, model::UnivariateAssumeDemoModels
 )
@@ -654,6 +661,31 @@ function posterior_mean(model::MultivariateAssumeDemoModels)
 
     return vals
 end
+function likelihood_optima(model::DynamicPPL.TestUtils.MultivariateAssumeDemoModels)
+    # Get some containers to fill.
+    vals = Random.rand(model)
+
+    # NOTE: These are "as close to zero as we can get".
+    vals.s[1] = 1e-32
+    vals.s[2] = 1e-32
+
+    vals.m[1] = 1.5
+    vals.m[2] = 2.0
+
+    return vals
+end
+function posterior_optima(model::DynamicPPL.TestUtils.MultivariateAssumeDemoModels)
+    # Get some containers to fill.
+    vals = Random.rand(model)
+
+    # TODO: Figure out exact for `s[1]`.
+    vals.s[1] = 0.890625
+    vals.s[2] = 1
+    vals.m[1] = 3 / 4
+    vals.m[2] = 1
+
+    return vals
+end
 function Random.rand(
     rng::Random.AbstractRNG, ::Type{NamedTuple}, model::MultivariateAssumeDemoModels
 )
@@ -684,6 +716,31 @@ function posterior_mean(model::MatrixvariateAssumeDemoModels)
 
     return vals
 end
+function likelihood_optima(model::DynamicPPL.TestUtils.MatrixvariateAssumeDemoModels)
+    # Get some containers to fill.
+    vals = Random.rand(model)
+
+    # NOTE: These are "as close to zero as we can get".
+    vals.s[1, 1] = 1e-32
+    vals.s[1, 2] = 1e-32
+
+    vals.m[1] = 1.5
+    vals.m[2] = 2.0
+
+    return vals
+end
+function posterior_optima(model::DynamicPPL.TestUtils.MatrixvariateAssumeDemoModels)
+    # Get some containers to fill.
+    vals = Random.rand(model)
+
+    # TODO: Figure out exact for `s[1]`.
+    vals.s[1, 1] = 0.890625
+    vals.s[1, 2] = 1
+    vals.m[1] = 3 / 4
+    vals.m[2] = 1
+
+    return vals
+end
 function Base.rand(
     rng::Random.AbstractRNG, ::Type{NamedTuple}, model::MatrixvariateAssumeDemoModels
 )