diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index aaf2c882dc1..d83acc73142 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,9 @@
+2009-07-15  Janus Weil  <janus@gcc.gnu.org>
+
+	PR fortran/40743
+	* resolve.c (resolve_symbol): Don't resolve the formal namespace of a
+	contained procedure.
+
 2009-07-14  Taras Glek  <tglek@mozilla.com>
 	    Rafael Espindola  <espindola@google.com>
 
diff --git a/gcc/fortran/resolve.c b/gcc/fortran/resolve.c
index 880dfd0e886..5b4fc2d6949 100644
--- a/gcc/fortran/resolve.c
+++ b/gcc/fortran/resolve.c
@@ -9842,7 +9842,8 @@ resolve_symbol (gfc_symbol *sym)
   formal_arg_flag = 0;
 
   /* Resolve formal namespaces.  */
-  if (sym->formal_ns && sym->formal_ns != gfc_current_ns)
+  if (sym->formal_ns && sym->formal_ns != gfc_current_ns
+      && !sym->attr.contained)
     gfc_resolve (sym->formal_ns);
 
   /* Make sure the formal namespace is present.  */
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 6f30aef5fcc..4dc08012919 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2009-07-15  Janus Weil  <janus@gcc.gnu.org>
+
+	PR fortran/40743
+	* gfortran.dg/interface_assignment_4.f90: New.
+
 2009-07-15  Gerald Pfeifer  <gerald@pfeifer.com>
 
 	* gcc.dg/builtins-config.h (HAVE_C99_RUNTIME): Do not define
diff --git a/gcc/testsuite/gfortran.dg/interface_assignment_4.f90 b/gcc/testsuite/gfortran.dg/interface_assignment_4.f90
new file mode 100644
index 00000000000..535e8842549
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/interface_assignment_4.f90
@@ -0,0 +1,35 @@
+! { dg-do compile }
+!
+! PR 40743: [4.5 Regression] ICE when compiling iso_varying_string.f95 at revision 149591
+!
+! Reduced from http://www.fortran.com/iso_varying_string.f95
+! Contributed by Janus Weil <janus@gcc.gnu.org>
+
+  implicit none
+
+  type :: varying_string
+  end type
+
+  interface assignment(=)
+     procedure op_assign_VS_CH
+  end interface
+
+contains
+
+  subroutine op_assign_VS_CH (var, exp)
+    type(varying_string), intent(out) :: var
+    character(LEN=*), intent(in)      :: exp
+  end subroutine
+
+  subroutine split_VS
+    type(varying_string) :: string
+    call split_CH(string)
+  end subroutine
+
+  subroutine split_CH (string)
+    type(varying_string) :: string
+    string = ""
+  end subroutine
+
+end
+