diff --git a/ssa/func.go b/ssa/func.go
index 13ef513a..3890bff7 100644
--- a/ssa/func.go
+++ b/ssa/func.go
@@ -16,6 +16,10 @@
 
 package ssa
 
+import (
+	"github.com/goplus/llvm"
+)
+
 // Function represents the parameters, results, and code of a function
 // or method.
 //
@@ -66,4 +70,5 @@ package ssa
 // the generic method. TypeArgs() refers to [string,U] or [string,int],
 // respectively, and is nil in the generic method.
 type Function struct {
+	impl llvm.Value
 }
diff --git a/ssa/package.go b/ssa/package.go
index cb03fd01..1c897fc7 100644
--- a/ssa/package.go
+++ b/ssa/package.go
@@ -81,7 +81,8 @@ func (p *Package) NewVar(name string, typ types.Type) *Global {
 }
 
 func (p *Package) NewFunc(name string, sig *types.Signature) *Function {
-	return &Function{}
+	fn := llvm.AddFunction(p.mod, name, p.prog.llvmSignature(sig))
+	return &Function{fn}
 }
 
 func (p *Package) String() string {
diff --git a/ssa/ssa_test.go b/ssa/ssa_test.go
index 743ac761..eed37539 100644
--- a/ssa/ssa_test.go
+++ b/ssa/ssa_test.go
@@ -78,3 +78,16 @@ source_filename = "foo/bar"
 @a = external global %Empty
 `)
 }
+
+func TestFunc(t *testing.T) {
+	prog := NewProgram(nil)
+	pkg := prog.NewPackage("bar", "foo/bar")
+	params := types.NewTuple(types.NewVar(0, nil, "a", types.Typ[types.Int]))
+	sig := types.NewSignatureType(nil, nil, nil, params, nil, false)
+	pkg.NewFunc("fn", sig)
+	assertPkg(t, pkg, `; ModuleID = 'foo/bar'
+source_filename = "foo/bar"
+
+declare void @fn(i64)
+`)
+}
diff --git a/ssa/type.go b/ssa/type.go
index b752effe..d4a87ea9 100644
--- a/ssa/type.go
+++ b/ssa/type.go
@@ -38,6 +38,15 @@ func (p *Program) llvmType(typ types.Type) llvm.Type {
 	return ret
 }
 
+func (p *Program) llvmSignature(sig *types.Signature) llvm.Type {
+	if v := p.typs.At(sig); v != nil {
+		return v.(llvm.Type)
+	}
+	ret := p.toLLVMFunc(sig)
+	p.typs.Set(sig, ret)
+	return ret
+}
+
 func (p *Program) tyVoidPtr() llvm.Type {
 	if p.voidPtrTy.IsNil() {
 		p.voidPtrTy = llvm.PointerType(p.tyVoid(), 0)