diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index c6e6d7eb64a..92a757096bf 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,9 @@
+2007-10-12  Paul Thomas  <pault@gcc.gnu.org>
+
+	PR fortran/33542
+	* resolve.c (resolve_actual_arglist): If the actual argument is
+	ambiguous, then there is an error.
+
 2007-10-12  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/33664
diff --git a/gcc/fortran/resolve.c b/gcc/fortran/resolve.c
index 2686c3dac82..26c139c84b8 100644
--- a/gcc/fortran/resolve.c
+++ b/gcc/fortran/resolve.c
@@ -971,6 +971,13 @@ resolve_actual_arglist (gfc_actual_arglist *arg, procedure_type ptype)
 	  continue;
 	}
 
+      if (e->expr_type == FL_VARIABLE && e->symtree->ambiguous)
+	{
+	  gfc_error ("'%s' at %L is ambiguous", e->symtree->n.sym->name,
+		     &e->where);
+	  return FAILURE;
+	}
+
       if (e->ts.type != BT_PROCEDURE)
 	{
 	  if (gfc_resolve_expr (e) != SUCCESS)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 890da97d183..cd64825f97b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2007-10-12  Paul Thomas  <pault@gcc.gnu.org>
+
+	PR fortran/33542
+	* gfortran.dg/ambiguous_specific_1.f90: New test.
+
 2007-10-12  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/33664
diff --git a/gcc/testsuite/gfortran.dg/ambiguous_specific_1.f90 b/gcc/testsuite/gfortran.dg/ambiguous_specific_1.f90
new file mode 100644
index 00000000000..b5292b2dd82
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/ambiguous_specific_1.f90
@@ -0,0 +1,38 @@
+! { dg-do compile }
+! Checks the fix for PR33542, in which the ambiguity in the specific
+! interfaces of foo was missed.
+!
+! Contributed by Tobias Burnus <burnus@gcc.gnu.org>
+!
+MODULE M1
+   INTERFACE FOO
+     MODULE PROCEDURE FOO
+   END INTERFACE
+CONTAINS
+   SUBROUTINE FOO(I)
+     INTEGER, INTENT(IN) :: I
+     WRITE(*,*) 'INTEGER'
+   END SUBROUTINE FOO
+END MODULE M1
+
+MODULE M2
+   INTERFACE FOO
+     MODULE PROCEDURE FOO
+   END INTERFACE
+CONTAINS
+   SUBROUTINE FOO(R)
+     REAL, INTENT(IN) :: R
+     WRITE(*,*) 'REAL'
+   END SUBROUTINE FOO
+END MODULE M2
+
+PROGRAM P
+   USE M1
+   USE M2
+   implicit none
+   external bar
+   CALL FOO(10)
+   CALL FOO(10.)
+   call bar (foo)  ! { dg-error "is ambiguous" }
+END PROGRAM P
+! { dg-final { cleanup-modules "m1 m2" } }