diff --git a/src/cmd/compile/internal/ssa/expand_calls.go b/src/cmd/compile/internal/ssa/expand_calls.go
index 91ff9f87f93..a3cea855f2f 100644
--- a/src/cmd/compile/internal/ssa/expand_calls.go
+++ b/src/cmd/compile/internal/ssa/expand_calls.go
@@ -954,11 +954,11 @@ func (x *expandState) storeArgOrLoad(pos src.XPos, b *Block, source, mem *Value,
 		elt := t.Elem()
 		if source.Type != t && t.NumElem() == 1 && elt.Size() == t.Size() && t.Size() == x.regSize {
 			t = removeTrivialWrapperTypes(t)
-			source.Type = t
 			// it could be a leaf type, but the "leaf" could be complex64 (for example)
 			return x.storeArgOrLoad(pos, b, source, mem, t, storeOffset, loadRegOffset, storeRc)
 		}
 		eltRO := x.regWidth(elt)
+		source.Type = t
 		for i := int64(0); i < t.NumElem(); i++ {
 			sel := source.Block.NewValue1I(pos, OpArraySelect, elt, i, source)
 			mem = x.storeArgOrLoad(pos, b, sel, mem, elt, storeOffset+i*elt.Size(), loadRegOffset, storeRc.at(t, 0))
@@ -988,11 +988,11 @@ func (x *expandState) storeArgOrLoad(pos src.XPos, b *Block, source, mem *Value,
 			// v139 is later stored as an intVal == struct{val *big.Int} which naively requires the fields of
 			// of a *uint8, which does not succeed.
 			t = removeTrivialWrapperTypes(t)
-			source.Type = t
 			// it could be a leaf type, but the "leaf" could be complex64 (for example)
 			return x.storeArgOrLoad(pos, b, source, mem, t, storeOffset, loadRegOffset, storeRc)
 		}
 
+		source.Type = t
 		for i := 0; i < t.NumFields(); i++ {
 			fld := t.Field(i)
 			sel := source.Block.NewValue1I(pos, OpStructSelect, fld.Type, int64(i), source)
diff --git a/test/fixedbugs/issue49378.go b/test/fixedbugs/issue49378.go
new file mode 100644
index 00000000000..70f466c929f
--- /dev/null
+++ b/test/fixedbugs/issue49378.go
@@ -0,0 +1,25 @@
+// compile
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func f(i int) {
+	var s1 struct {
+		s struct{ s struct{ i int } }
+	}
+	var s2, s3 struct {
+		a struct{ i int }
+		b int
+	}
+	func() {
+		i = 1 + 2*i + s3.a.i + func() int {
+			s2.a, s2.b = s3.a, s3.b
+			return 0
+		}() + func(*int) int {
+			return s1.s.s.i
+		}(new(int))
+	}()
+}