3 files changed, 12 insertions, 2 deletions
diff --git a/eval.cc b/eval.cc
index f21e185..3dfc0e6 100644
--- a/eval.cc
+++ b/eval.cc
@@ -54,9 +54,12 @@ Var* Evaluator::EvalRHS(Symbol lhs, Value* rhs_v, StringPiece orig_rhs,
   Var* rhs = NULL;
   bool needs_assign = true;
   switch (op) {
-    case AssignOp::COLON_EQ:
-      rhs = new SimpleVar(rhs_v->Eval(this), origin);
+    case AssignOp::COLON_EQ: {
+      SimpleVar* sv = new SimpleVar(origin);
+      rhs_v->Eval(this, sv->mutable_value());
+      rhs = sv;
       break;
+    }
     case AssignOp::EQ:
       rhs = new RecursiveVar(rhs_v, origin, orig_rhs);
       break;
diff --git a/var.cc b/var.cc
index d21dc4f..9fac956 100644
--- a/var.cc
+++ b/var.cc
@@ -47,6 +47,10 @@ void Var::AppendVar(Evaluator*, Value*) {
   CHECK(false);
 }
 
+SimpleVar::SimpleVar(VarOrigin origin)
+    : origin_(origin) {
+}
+
 SimpleVar::SimpleVar(const string& v, VarOrigin origin)
     : v_(v), origin_(origin) {
 }
diff --git a/var.h b/var.h
index 3bae262..c3bb233 100644
--- a/var.h
+++ b/var.h
@@ -62,6 +62,7 @@ class Var : public Evaluable {
 
 class SimpleVar : public Var {
  public:
+  explicit SimpleVar(VarOrigin origin);
   SimpleVar(const string& v, VarOrigin origin);
 
   virtual const char* Flavor() const {
@@ -79,6 +80,8 @@ class SimpleVar : public Var {
 
   virtual string DebugString() const override;
 
+  string* mutable_value() { return &v_; }
+
  private:
   string v_;
   VarOrigin origin_;