diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index f00ef845158..8d2663ba23e 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2009-12-16  Jason Merrill  <jason@redhat.com>
+
+	PR c++/42387
+	* decl.c (compute_array_index_type): Mark a VLA as dependent.
+
 2009-12-15  Jason Merrill  <jason@redhat.com>
 
 	PR c++/42358
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 5b37ef7e710..1c3f2efe32a 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -7270,11 +7270,8 @@ compute_array_index_type (tree name, tree size)
 	 structural equality checks.  */
       itype = build_index_type (build_min (MINUS_EXPR, sizetype,
 					   size, integer_one_node));
-      if (!TREE_SIDE_EFFECTS (size))
-	{
-	  TYPE_DEPENDENT_P (itype) = 1;
-	  TYPE_DEPENDENT_P_VALID (itype) = 1;
-	}
+      TYPE_DEPENDENT_P (itype) = 1;
+      TYPE_DEPENDENT_P_VALID (itype) = 1;
       SET_TYPE_STRUCTURAL_EQUALITY (itype);
       return itype;
     }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index d0c09850252..d2beaf38ab1 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2009-12-15  Jason Merrill  <jason@redhat.com>
+
+	PR c++/42387
+	* g++.dg/ext/vla8.C: New.
+
 2009-12-16  Jakub Jelinek  <jakub@redhat.com>
 
 	* gcc.c-torture/compile/20091215-1.c: New test.
diff --git a/gcc/testsuite/g++.dg/ext/vla8.C b/gcc/testsuite/g++.dg/ext/vla8.C
new file mode 100644
index 00000000000..7b7428d07a9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/vla8.C
@@ -0,0 +1,15 @@
+// PR c++/42387
+// { dg-options "" }
+
+template<class PF>
+struct AvlTreeIter
+{
+  int Num();
+
+  AvlTreeIter()
+  {
+    new (void* [Num()]);
+  }
+};
+
+AvlTreeIter<int> a;