diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index e0d24ec3e10..d7fd5ea56f6 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2005-09-13  Mark Mitchell  <mark@codesourcery.com>
+
+	PR c++/23839
+	* typeck.c (cxx_mark_addressable): Only check DECL_HARD_REGISTER
+	for VAR_DECLs.
+
 2005-09-13  Mark Mitchell  <mark@codesourcery.com>
 
 	PR c++/23842
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index b0dfa604d89..76ae5104b16 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -4340,7 +4340,7 @@ cxx_mark_addressable (tree exp)
 	if (DECL_REGISTER (x) && !TREE_ADDRESSABLE (x)
 	    && !DECL_ARTIFICIAL (x))
 	  {
-	    if (DECL_HARD_REGISTER (x) != 0)
+	    if (TREE_CODE (x) == VAR_DECL && DECL_HARD_REGISTER (x))
 	      {
 		error
 		  ("address of explicit register variable %qD requested", x);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 5322f23a28d..8aaa1697078 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2005-09-13  Mark Mitchell  <mark@codesourcery.com>
+
+	PR c++/23839
+	* g++.dg/parse/register1.C: New test.
+
 2005-09-13  Mark Mitchell  <mark@codesourcery.com>
 
 	PR c++/23842
diff --git a/gcc/testsuite/g++.dg/parse/register1.C b/gcc/testsuite/g++.dg/parse/register1.C
new file mode 100644
index 00000000000..3be2e652502
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/register1.C
@@ -0,0 +1,14 @@
+// PR c++/23839
+
+class C
+{
+  int i;
+public:
+  C(int j) : i(j) { }
+  operator int() { return i; }
+};
+
+C f (register C x)
+{
+  return x + 31;
+}