diff --git a/src/linearmixedmodel.jl b/src/linearmixedmodel.jl
index f78f2320a..978863402 100644
--- a/src/linearmixedmodel.jl
+++ b/src/linearmixedmodel.jl
@@ -43,7 +43,12 @@ LinearMixedModel(f::FormulaTerm, tbl;
 function LinearMixedModel(f::FormulaTerm, tbl::Tables.ColumnTable;
                           contrasts = Dict{Symbol,Any}(),
                           wts = [])
+    # TODO: perform missing_omit() after apply_schema() when improved
+    # missing support is in a StatsModels release
+    tbl, _ = StatsModels.missing_omit(tbl, f)
     form = apply_schema(f, schema(f, tbl, contrasts), LinearMixedModel)
+    # tbl, _ = StatsModels.missing_omit(tbl, form)
+
     y, Xs = modelcols(form, tbl)
 
     y = reshape(float(y), (:, 1)) # y as a floating-point matrix
diff --git a/src/randomeffectsterm.jl b/src/randomeffectsterm.jl
index 6fb0530bb..52f7bf4dc 100644
--- a/src/randomeffectsterm.jl
+++ b/src/randomeffectsterm.jl
@@ -1,11 +1,22 @@
 struct RandomEffectsTerm <: AbstractTerm
     lhs::StatsModels.TermOrTerms
     rhs::StatsModels.TermOrTerms
+    function RandomEffectsTerm(lhs,rhs)
+        if isempty(intersect(StatsModels.termvars(lhs), StatsModels.termvars(rhs)))
+            new(lhs, rhs)
+        else
+            throw(ArgumentError("Same variable appears on both sides of |"))
+        end
+    end
 end
 
 Base.show(io::IO, t::RandomEffectsTerm) = print(io, "($(t.lhs) | $(t.rhs))")
 StatsModels.is_matrix_term(::Type{RandomEffectsTerm}) = false
 
+function StatsModels.termvars(t::RandomEffectsTerm)
+    vcat(StatsModels.termvars(t.lhs), StatsModels.termvars(t.rhs))
+end
+
 function StatsModels.apply_schema(t::FunctionTerm{typeof(|)}, schema::StatsModels.FullRank,
         Mod::Type{<:MixedModel})
     lhs, rhs = apply_schema.(t.args_parsed, Ref(schema), Mod)
diff --git a/test/FactorReTerm.jl b/test/FactorReTerm.jl
index e207a2361..ef75c0304 100644
--- a/test/FactorReTerm.jl
+++ b/test/FactorReTerm.jl
@@ -79,6 +79,24 @@ const LMM = LinearMixedModel
     end
 end
 
+@testset "RandomEffectsTerm" begin
+    slp = dat[:sleepstudy]
+    contrasts =  Dict{Symbol,Any}()
+
+    @testset "Detect same variable as blocking and experimental" begin
+        f = @formula(Y ~ 1 + (1 + G|G))
+        @test_throws ArgumentError apply_schema(f, schema(f, slp, contrasts), LinearMixedModel)
+    end
+
+    @testset "Detect both blocking and experimental variables" begin
+        # note that U is not in the fixed effects because we want to make square
+        # that we're detecting all the variables in the random effects
+        f = @formula(Y ~ 1 + (1 + U|G))
+        form = apply_schema(f, schema(f, slp, contrasts), LinearMixedModel)
+        @test StatsModels.termvars(form.rhs) == [:U, :G]
+    end
+end
+
 #=
 @testset "vectorRe" begin
     slp = dat[:sleepstudy]
diff --git a/test/missing.jl b/test/missing.jl
new file mode 100644
index 000000000..8a5a8a68a
--- /dev/null
+++ b/test/missing.jl
@@ -0,0 +1,37 @@
+using MixedModels, RData, Test
+
+if !@isdefined(dat) || !isa(dat, Dict{Symbol, DataFrame})
+    const dat = Dict(Symbol(k) => v for (k, v) in
+        load(joinpath(dirname(pathof(MixedModels)), "..", "test", "dat.rda")))
+end
+
+# deepcopy because we're going to modify it
+slp = deepcopy(dat[:sleepstudy])
+slp[!,:U] = Array{Union{Missing, Float64},1}(slp[!,:U])
+slp[1,:U] = missing
+
+# TODO: re-enable this test when better missing support has landed in StatsModels
+# @testset "No impact from missing on schema" begin
+#     f = @formula(Y ~ 1 + U + (1|G))
+#     contrasts =  Dict{Symbol,Any}()
+#     form = apply_schema(f, schema(f, dat[:sleepstudy], contrasts), LinearMixedModel)
+#     form_missing = apply_schema(f, schema(f, slp, contrasts), LinearMixedModel)
+#
+#     @test form.lhs == form_missing.lhs
+#     @test form.rhs == form_missing.rhs
+# end
+
+@testset "Missing Omit" begin
+    @testset "Missing from unused variables" begin
+        # missing from unused variables should have no impact
+        m1 = fit(MixedModel, @formula(Y ~ 1 + (1|G)), dat[:sleepstudy])
+        m1_missing = fit(MixedModel, @formula(Y ~ 1 + (1|G)), slp)
+        @test isapprox(m1.θ, m1_missing.θ, rtol=1.0e-12)
+    end
+
+    @testset "Missing from used variables" begin
+        m1 = fit(MixedModel, @formula(Y ~ 1 + U + (1|G)), dat[:sleepstudy])
+        m1_missing = fit(MixedModel, @formula(Y ~ 1 + U + (1|G)), slp)
+        @test nobs(m1) - nobs(m1_missing) == 1
+    end
+end
diff --git a/test/runtests.jl b/test/runtests.jl
index d2ff194c9..887b9a10e 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -11,5 +11,6 @@ include("pls.jl")
 include("pirls.jl")
 include("gausshermite.jl")
 include("fit.jl")
+include("missing.jl")
 
 using MixedModels