diff --git a/cl/_testrt/map/out.ll b/cl/_testrt/map/out.ll
index 19de1043..a2e179d1 100644
--- a/cl/_testrt/map/out.ll
+++ b/cl/_testrt/map/out.ll
@@ -30,12 +30,16 @@ _llgo_0:
   call void @main.init()
   %2 = call ptr @"github.com/goplus/llgo/internal/runtime.MakeSmallMap"()
   %3 = load ptr, ptr @"map[_llgo_int]_llgo_int", align 8
-  %4 = call ptr @"github.com/goplus/llgo/internal/runtime.MapAssign"(ptr %3, ptr %2, i64 23)
-  store i64 100, ptr %4, align 4
-  %5 = load ptr, ptr @"map[_llgo_int]_llgo_int", align 8
-  %6 = call ptr @"github.com/goplus/llgo/internal/runtime.MapAssign"(ptr %5, ptr %2, i64 7)
-  store i64 29, ptr %6, align 4
-  %7 = call i32 (ptr, ...) @printf(ptr @0, <null operand!>)
+  %4 = alloca i8, i64 48, align 1
+  store ptr %2, ptr %4, align 8
+  %5 = call ptr @"github.com/goplus/llgo/internal/runtime.MapAssign"(ptr %3, ptr %4, i64 23)
+  store i64 100, ptr %5, align 4
+  %6 = load ptr, ptr @"map[_llgo_int]_llgo_int", align 8
+  %7 = alloca i8, i64 48, align 1
+  store ptr %2, ptr %7, align 8
+  %8 = call ptr @"github.com/goplus/llgo/internal/runtime.MapAssign"(ptr %6, ptr %7, i64 7)
+  store i64 29, ptr %8, align 4
+  %9 = call i32 (ptr, ...) @printf(ptr @0, <null operand!>)
   ret i32 0
 }
 
diff --git a/ssa/datastruct.go b/ssa/datastruct.go
index 0070e160..bac55714 100644
--- a/ssa/datastruct.go
+++ b/ssa/datastruct.go
@@ -366,7 +366,8 @@ func (b Builder) MapUpdate(m, k, v Expr) {
 	}
 	tabi := b.abiType(t.raw.Type)
 	prog := b.Prog
-	ptrimpl := b.InlineCall(b.Pkg.rtFunc("MapAssign"), tabi, m, k).impl
+	mptr := b.dupAlloca(m)
+	ptrimpl := b.InlineCall(b.Pkg.rtFunc("MapAssign"), tabi, mptr, k).impl
 	ptr := Expr{ptrimpl, prog.Pointer(v.Type)}
 	b.Store(ptr, v) // TODO(xsw): indirect store
 }
diff --git a/ssa/memory.go b/ssa/memory.go
index d63df457..8ece634c 100644
--- a/ssa/memory.go
+++ b/ssa/memory.go
@@ -107,16 +107,15 @@ func aggregateInit(b llvm.Builder, ptr llvm.Value, tll llvm.Type, flds ...llvm.V
 	}
 }
 
-/*
-func (b Builder) dupMalloc(v Expr) Expr {
+func (b Builder) dupAlloca(v Expr) Expr {
 	prog := b.Prog
 	n := prog.SizeOf(v.Type)
 	tptr := prog.Pointer(v.Type)
-	ptr := b.malloc(prog.Val(uintptr(n))).impl
-	b.Store(Expr{ptr, tptr}, v)
-	return Expr{ptr, tptr}
+	ptr := b.Alloca(prog.Val(uintptr(n))).impl
+	ret := Expr{ptr, tptr}
+	b.Store(ret, v)
+	return ret
 }
-*/
 
 // -----------------------------------------------------------------------------