diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index d721bdf9746771770a7e451def49523e42464a92..c6bc662202b2d6839044776f37bdf4f33b5c0dc3 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,9 @@
+2016-09-26  Steven G. Kargl  <kargl@gcc.gnu.org>
+
+	PR fortran/77420
+	* trans-common.c:  Handle array elements in equivalence when
+	the lower and upper bounds of array spec are NULL.
+
 2016-09-26  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/48298
diff --git a/gcc/fortran/trans-common.c b/gcc/fortran/trans-common.c
index 20ec69eb5701c327314446ec250e9ae740587f54..ee12fa22dc052bc0b46952584dab3d838bc22b75 100644
--- a/gcc/fortran/trans-common.c
+++ b/gcc/fortran/trans-common.c
@@ -805,13 +805,21 @@ element_number (gfc_array_ref *ar)
       if (ar->dimen_type[i] != DIMEN_ELEMENT)
         gfc_internal_error ("element_number(): Bad dimension type");
 
-      mpz_sub (n, *get_mpz (ar->start[i]), *get_mpz (as->lower[i]));
+      if (as && as->lower[i])
+	mpz_sub (n, *get_mpz (ar->start[i]), *get_mpz (as->lower[i]));
+      else
+	mpz_sub_ui (n, *get_mpz (ar->start[i]), 1);
  
       mpz_mul (n, n, multiplier);
       mpz_add (offset, offset, n);
  
-      mpz_sub (extent, *get_mpz (as->upper[i]), *get_mpz (as->lower[i]));
-      mpz_add_ui (extent, extent, 1);
+      if (as && as->upper[i] && as->lower[i])
+	{
+	  mpz_sub (extent, *get_mpz (as->upper[i]), *get_mpz (as->lower[i]));
+	  mpz_add_ui (extent, extent, 1);
+	}
+      else
+	mpz_set_ui (extent, 0);
  
       if (mpz_sgn (extent) < 0)
         mpz_set_ui (extent, 0);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b9b0996767554e09954c64ed9afce2998107adb8..446848f2760ecfeea470661ea41775fa90d51b6e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2016-09-26  Steven G. Kargl  <kargl@gcc.gnu.org>
+
+	PR fortran/77420
+	* gfortran.dg/pr77420_1.f90: New test.
+	* gfortran.dg/pr77420_2.f90: Ditto.
+	* gfortran.dg/pr77420_3.f90: New test. Requires ...
+	* gfortran.dg/pr77420_4.f90: this file.
+
 2016-09-26  Kugan Vivekanandarajah  <kuganv@linaro.org>
 
 	PR middle-end/77719
diff --git a/gcc/testsuite/gfortran.dg/pr77420_1.f90 b/gcc/testsuite/gfortran.dg/pr77420_1.f90
new file mode 100644
index 0000000000000000000000000000000000000000..7652d6950fa2f41e910caeb3f1d9333477f7e87e
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr77420_1.f90
@@ -0,0 +1,15 @@
+! { dg-do compile }
+module test_equivalence
+  real, private :: array1(100)
+  real, private :: array2(100)
+  equivalence(array1(3),array2(3))
+end module test_equivalence
+
+module mymodule
+  use test_equivalence
+  real, dimension(:), allocatable :: array1
+end module mymodule
+
+program test
+  use mymodule
+end program test
diff --git a/gcc/testsuite/gfortran.dg/pr77420_2.f90 b/gcc/testsuite/gfortran.dg/pr77420_2.f90
new file mode 100644
index 0000000000000000000000000000000000000000..4826801a2dcecbcbf54cd8feca8151e8f70a52d4
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr77420_2.f90
@@ -0,0 +1,15 @@
+! { dg-do compile }
+module test_equivalence
+  real, private :: array1(100)
+  real, private :: array2(100)
+  equivalence(array1,array2)
+end module test_equivalence
+
+module mymodule
+  use test_equivalence
+  real, dimension(:), allocatable :: array1
+end module mymodule
+
+program test
+  use mymodule
+end program test
diff --git a/gcc/testsuite/gfortran.dg/pr77420_3.f90 b/gcc/testsuite/gfortran.dg/pr77420_3.f90
new file mode 100644
index 0000000000000000000000000000000000000000..cf95ac05f83d1f2e3feeba0d3e26a9863d3a810d
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr77420_3.f90
@@ -0,0 +1,9 @@
+! { dg-do link }
+! { dg-additional-sources pr77420_4.f90 }
+!
+module h5global
+  implicit none
+  integer :: h5p_default_f, h5p_flags
+  equivalence(h5p_flags, h5p_default_f)
+end module h5global
+! { dg-final { cleanup-modules "h5global" } }
diff --git a/gcc/testsuite/gfortran.dg/pr77420_4.f90 b/gcc/testsuite/gfortran.dg/pr77420_4.f90
new file mode 100644
index 0000000000000000000000000000000000000000..5eee0986b809806b127477ae63996d8926cb70c5
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr77420_4.f90
@@ -0,0 +1,8 @@
+! { dg-do compile { target { ! *-*-* } } }
+!
+program bug
+  use H5GLOBAL
+  implicit none
+  integer :: i
+  i=H5P_DEFAULT_F
+end program bug