diff --git a/tgt-vhdl/expr.cc b/tgt-vhdl/expr.cc
index dc69cd687..b5a76ca37 100644
--- a/tgt-vhdl/expr.cc
+++ b/tgt-vhdl/expr.cc
@@ -58,9 +58,14 @@ static vhdl_var_ref *translate_signal(ivl_expr_t e)
 
    const char *renamed = get_renamed_signal(sig).c_str();
    
-   const vhdl_decl *decl = scope->get_decl(renamed);
+   vhdl_decl *decl = scope->get_decl(renamed);
    assert(decl);
 
+   // Can't generate a constant initialiser for this signal
+   // later as it has already been read
+   if (scope->initializing())
+      decl->set_initial(NULL);
+
    vhdl_type *type = new vhdl_type(*decl->get_type());
    
    return new vhdl_var_ref(renamed, type);
diff --git a/tgt-vhdl/process.cc b/tgt-vhdl/process.cc
index 57326a11e..7333dff2b 100644
--- a/tgt-vhdl/process.cc
+++ b/tgt-vhdl/process.cc
@@ -40,8 +40,8 @@ static int generate_vhdl_process(vhdl_entity *ent, ivl_process_t proc)
 
    // If this is an initial process, push signal initialisation
    // into the declarations
-   if (ivl_process_type(proc) == IVL_PR_INITIAL)
-      vhdl_proc->get_scope()->set_initializing(true);
+   vhdl_proc->get_scope()->set_initializing
+      (ivl_process_type(proc) == IVL_PR_INITIAL);
    
    ivl_statement_t stmt = ivl_process_stmt(proc);
    int rc = draw_stmt(vhdl_proc, vhdl_proc->get_container(), stmt);
diff --git a/tgt-vhdl/vhdl_syntax.cc b/tgt-vhdl/vhdl_syntax.cc
index c0b1e3060..af65ee0a1 100644
--- a/tgt-vhdl/vhdl_syntax.cc
+++ b/tgt-vhdl/vhdl_syntax.cc
@@ -28,7 +28,7 @@
 vhdl_scope::vhdl_scope()
    : parent_(NULL), init_(false), sig_assign_(true)
 {
-
+   
 }
 
 vhdl_scope::~vhdl_scope()
@@ -36,6 +36,13 @@ vhdl_scope::~vhdl_scope()
    delete_children<vhdl_decl>(decls_);
 }
 
+void vhdl_scope::set_initializing(bool i)
+{
+   init_ = i;
+   if (parent_)
+      parent_->set_initializing(i);
+}
+
 void vhdl_scope::add_decl(vhdl_decl *decl)
 {
    decls_.push_back(decl);
@@ -318,10 +325,12 @@ const vhdl_type *vhdl_decl::get_type() const
 }
 
 void vhdl_decl::set_initial(vhdl_expr *initial)
-{
-   if (initial_ != NULL)
-      delete initial_;
-   initial_ = initial;
+{   
+   if (!has_initial_) {
+      assert(initial_ == NULL);
+      initial_ = initial;
+      has_initial_ = true;
+   }
 }
 
 void vhdl_port_decl::emit(std::ostream &of, int level) const
diff --git a/tgt-vhdl/vhdl_syntax.hh b/tgt-vhdl/vhdl_syntax.hh
index d76370b37..5fa684e21 100644
--- a/tgt-vhdl/vhdl_syntax.hh
+++ b/tgt-vhdl/vhdl_syntax.hh
@@ -425,18 +425,20 @@ class vhdl_decl : public vhdl_element {
 public:
    vhdl_decl(const char *name, vhdl_type *type = NULL,
              vhdl_expr *initial = NULL)
-      : name_(name), type_(type), initial_(initial) {}
+      : name_(name), type_(type), initial_(initial),
+        has_initial_(initial != NULL) {}
    virtual ~vhdl_decl();
 
    const std::string &get_name() const { return name_; }
    const vhdl_type *get_type() const;
    void set_type(vhdl_type *t) { type_ = t; }
    void set_initial(vhdl_expr *initial);
-   bool has_initial() const { return initial_ != NULL; }
+   bool has_initial() const { return has_initial_; }
 protected:
    std::string name_;
    vhdl_type *type_;
    vhdl_expr *initial_;
+   bool has_initial_;
 };
 
 typedef std::list<vhdl_decl*> decl_list_t;
@@ -566,7 +568,7 @@ public:
    void set_parent(vhdl_scope *p) { parent_ = p; }
 
    bool initializing() const { return init_; }
-   void set_initializing(bool i) { init_ = i; }
+   void set_initializing(bool i);
 
    void set_allow_signal_assignment(bool b) { sig_assign_ = b; }
    bool allow_signal_assignment() const { return sig_assign_; }