diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 9ebc6095b1d..357b925390d 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2010-02-18  Jason Merrill  <jason@redhat.com>
+
+	PR c++/43109
+	* semantics.c (begin_class_definition): Don't crash on unnamed ns.
+
 2010-02-17  Jason Merrill  <jason@redhat.com>
 
 	PR c++/43075
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 90a76d9391c..24390d98c0c 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -2378,6 +2378,7 @@ begin_class_definition (tree t, tree attributes)
       tree ns = TYPE_CONTEXT (t);
       if (ns && TREE_CODE (ns) == NAMESPACE_DECL
 	  && DECL_CONTEXT (ns) == std_node
+	  && DECL_NAME (ns)
 	  && !strcmp (IDENTIFIER_POINTER (DECL_NAME (ns)), "decimal"))
 	{
 	  const char *n = TYPE_NAME_STRING (t);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 9c82d351469..dbc8226220b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2010-02-18  Jason Merrill  <jason@redhat.com>
+
+	PR c++/43109
+	* g++.dg/parse/namespace12.C: New.
+
 2010-02-18  Martin Jambor  <mjambor@suse.cz>
 
 	PR tree-optimization/43066
diff --git a/gcc/testsuite/g++.dg/parse/namespace12.C b/gcc/testsuite/g++.dg/parse/namespace12.C
new file mode 100644
index 00000000000..25d6ae09309
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/namespace12.C
@@ -0,0 +1,7 @@
+// PR c++/43109
+
+namespace std {
+ namespace {
+   struct S {};
+ }
+}