diff --git a/ssa/type.go b/ssa/type.go
index 3b6e85f9..67c0ca17 100644
--- a/ssa/type.go
+++ b/ssa/type.go
@@ -114,7 +114,7 @@ func (p *goProgram) Offsetsof(fields []*types.Var) (ret []int64) {
 func (p *goProgram) Sizeof(T types.Type) int64 {
 	prog := Program(p)
 	ptrSize := int64(prog.PointerSize())
-	return prog.sizes.Sizeof(T) + extraSize(T, ptrSize)
+	return align((prog.sizes.Sizeof(T) + extraSize(T, ptrSize)), prog.sizes.Alignof(T))
 }
 
 func extraSize(t types.Type, ptrSize int64) (ret int64) {
@@ -134,6 +134,10 @@ func extraSize(t types.Type, ptrSize int64) (ret int64) {
 	return 0
 }
 
+func align(x, a int64) int64 {
+	return (x + a - 1) &^ (a - 1)
+}
+
 // -----------------------------------------------------------------------------
 
 type rawType struct {