diff --git a/lang/funcs/simple/simple.go b/lang/funcs/simple/simple.go
index 5d84ccdb4..8c382a90a 100644
--- a/lang/funcs/simple/simple.go
+++ b/lang/funcs/simple/simple.go
@@ -66,6 +66,9 @@ func Register(name string, fn *types.FuncValue) {
 	if fn.T.Kind != types.KindFunc {
 		panic(fmt.Sprintf("simple func %s must be of kind func", name))
 	}
+	if fn.T.HasUni() {
+		panic(fmt.Sprintf("simple func %s contains a unification variable", name))
+	}
 	if fn.T.HasVariant() {
 		panic(fmt.Sprintf("simple func %s contains a variant type signature", name))
 	}
diff --git a/lang/unification/fastsolver/fastsolver.go b/lang/unification/fastsolver/fastsolver.go
index 90cf4b6d4..ab8126532 100644
--- a/lang/unification/fastsolver/fastsolver.go
+++ b/lang/unification/fastsolver/fastsolver.go
@@ -31,6 +31,7 @@ package fastsolver
 
 import (
 	"context"
+	"fmt"
 	"strings"
 
 	"github.com/purpleidea/mgmt/lang/unification"
@@ -125,5 +126,23 @@ func (obj *FastInvariantSolver) Solve(ctx context.Context, data *unification.Dat
 		}
 	}
 
+	// XXX: Just guessing about this next step... Somehow I feel something is wrong...
+	// XXX: I also need to check if I have any unification vars left...
+	// XXX: I also need to collect a list of what I _want_ to solve for and make sure I did...
+	for _, x := range data.UnificationInvariants { // []*UnificationInvariant
+		if x.Expect == nil || x.Actual == nil {
+			return nil, fmt.Errorf("WAT0")
+		}
+		t1 := unificationUtil.Extract(x.Expect)
+		t2 := unificationUtil.Extract(x.Actual)
+
+		if err := t1.Cmp(t2); err != nil { // XXX Should be the same... ???
+			return nil, errwrap.Wrapf(err, "WAT1")
+		}
+		if err := x.Expr.SetType(t1); err != nil {
+			return nil, errwrap.Wrapf(err, "WAT2")
+		}
+	}
+
 	panic("not implemented") // XXX RETURN SOMETHING
 }