diff --git a/Project.toml b/Project.toml
index f776185..3351c90 100644
--- a/Project.toml
+++ b/Project.toml
@@ -5,6 +5,7 @@ version = "1.0.0-DEV"
 
 [deps]
 InteractiveUtils = "b77e0a4c-d291-57a0-90e8-8db25a27a240"
+IterTools = "c8e1da08-722c-5040-9ed9-7db0dc04731e"
 MacroTools = "1914dd2f-81c6-5fcd-8719-6d5c9610ff09"
 OrderedCollections = "bac558e1-5e72-5ebc-8fee-abe8a469f55d"
 
diff --git a/src/join_nodes.jl b/src/join_nodes.jl
index fab528e..84f009f 100644
--- a/src/join_nodes.jl
+++ b/src/join_nodes.jl
@@ -1,5 +1,6 @@
 
 using Base.Iterators: flatten
+using IterTools: repeatedly
 
 export JoinNode
 
@@ -12,15 +13,14 @@ to assert.
 """
 struct JoinNode <: AbstractReteJoinNode
     label::String
-    a_inputs   # ::Set{AbstractMemoryNode{T1}}
-    b_inputs   # ::Set{AbstractMemoryNode{T2}}
+    inputs
     outputs::Set{AbstractReteNode}
     join_function
 
-    JoinNode(label::String, join_function) =
+    JoinNode(label::String, input_arity, join_function) =
         new(label,
-            Set{AbstractMemoryNode}(),
-            Set{AbstractMemoryNode}(),
+            Tuple(repeatedly(() -> Set{AbstractMemoryNode}(),
+                             input_arity)),
             Set{AbstractReteNode}(),
             join_function)
 end
@@ -35,26 +35,36 @@ label(n::JoinNode) = n.label
 
 function connect(from::AbstractReteNode, to::JoinNode, input::Int)
     @assert input >= 1
-    @assert input <= 2
+    @assert input <= length(to.inputs)
     push!(from.outputs, to)
-    if input == 1
-        push!(to.a_inputs, from)
-    else
-        push!(to.b_inputs, from)
-    end
+    push!(to.inputs[input], from)
 end
 
 
 function receive(node::JoinNode, fact, from::AbstractMemoryNode)
-    if from in node.a_inputs
-        askc(node.b_inputs) do b_fact
-            node.join_function(node, fact, b_fact)
-        end
-    end
-    if from in node.b_inputs
-        askc(node.a_inputs) do a_fact
-            node.join_function(node, a_fact, fact)
+    args = Vector(undef, length(node.inputs))
+    last_from_pos = findlast(map(i -> from in i, node.inputs))
+    function helper(argnumber, hasfact)
+        if argnumber > length(args)
+            if hasfact
+                node.join_function(node, args...)
+            end
+        else
+            # Avoid computing more of the power set of arguments if
+            # we've not added fact and we've passed the last set of
+            # inputs that could contain from.
+            if !hasfact && argnumber > last_from_pos
+                return
+            end
+            for input in node.inputs[argnumber]
+                askc(input) do i_fact
+                    args[argnumber] = i_fact
+                    helper(argnumber + 1,
+                           hasfact || (i_fact == fact))
+                end
+            end
         end
     end
+    helper(1, false)    
 end
 
diff --git a/src/memory_nodes.jl b/src/memory_nodes.jl
index 076d2e7..3fcbfa6 100644
--- a/src/memory_nodes.jl
+++ b/src/memory_nodes.jl
@@ -43,10 +43,10 @@ function receive(node::IsaMemoryNode{T}, fact::T) where{T}
     if fact in node.memory
         return
     end
+    push!(node.memory, fact)
     for output in node.outputs
         emit(node, output, fact)
     end
-    push!(node.memory, fact)
 end
 
 
diff --git a/test/runtests.jl b/test/runtests.jl
index 91ef604..6a17962 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -39,7 +39,7 @@ end
     ints = IsaMemoryNode{Int}()
     connect(root, chars)
     connect(root, ints)
-    join = JoinNode("join char int",
+    join = JoinNode("join char int", 2,
                     function(node, c, i)
                         emit(node, "$c$i")
                     end)
@@ -54,15 +54,17 @@ end
     for i in 1:3
         receive(root, i)
     end
-    println(conclusions.memory)
-    @test conclusions.memory == Set{String}([
-        "a1", "b1", "c1", "a2", "b2", "c2", "a3", "b3", "c3"])
+    results = collecting() do c
+        askc(c, conclusions)
+    end
+    @test sort(results) ==
+        sort(["a1", "b1", "c1", "a2", "b2", "c2", "a3", "b3", "c3"])
 end
 
 @testset "symetric join test" begin
     root = BasicReteNode("root")
     ints = IsaMemoryNode{Int}()
-    join = JoinNode("join",
+    join = JoinNode("join", 2,
                     function(node, a, b)
                         if b == a + 1
                             emit(node, (a, b))
@@ -77,9 +79,41 @@ end
     for i in 1:5
         receive(root, i)
     end
-    @test conclusions.memory ==
-        Set{Tuple{Int, Int}}([
-            (1, 2), (2, 3), (3, 4), (4, 5)])
+    results = collecting() do c
+        askc(c, conclusions)
+    end
+    @test sort(results) ==
+        sort([(1, 2), (2, 3), (3, 4), (4, 5)])
+end
+
+@testset "3-ary join" begin
+    root = BasicReteNode("root")
+    ints = IsaMemoryNode{Int}()
+    chars = IsaMemoryNode{Char}()
+    join = JoinNode("join", 3,
+                    function(node, a, b, c)
+                        if a != c
+                            emit(node, "$a$b$c")
+                        end
+                    end)
+    conclusions = IsaMemoryNode{String}()
+    connect(root, ints)
+    connect(root, chars)
+    connect(root, conclusions)
+    connect(ints, join, 1)
+    connect(chars, join, 2)
+    connect(ints, join, 3)
+    connect(join, root)
+    for i in 1:2
+        receive(root, i)
+    end
+    for c in 'a':'b'
+        receive(root, c)
+    end
+    results = collecting() do c
+        askc(c, conclusions)
+    end
+    @test sort(results) == sort(["1a2", "2a1", "1b2", "2b1"])
 end
 
 @testset "ensure_IsaMemoryNode" begin