Index: gcc/fortran/module.c
===================================================================
--- gcc/fortran/module.c	(revision 143063)
+++ gcc/fortran/module.c	(working copy)
@@ -4337,6 +4337,7 @@
 {
   gfc_common_head *p;
   const char * name;
+  const char * lname;
   int flags;
   const char *label;
   struct written_common *w;
@@ -4349,6 +4350,9 @@
 
   /* We will write out the binding label, or the name if no label given.  */
   name = st->n.common->name;
+
+  /* Use the symtree(local)name to check if the common has been written.  */ 
+  lname = st->name;
   p = st->n.common;
   label = p->is_bind_c ? p->binding_label : p->name;
 
@@ -4356,7 +4360,7 @@
   w = written_commons;
   while (w)
     {
-      int c = strcmp (name, w->name);
+      int c = strcmp (lname, w->name);
       c = (c != 0 ? c : strcmp (label, w->label));
       if (c == 0)
 	write_me = false;
@@ -4384,7 +4388,7 @@
 
       /* Record that we have written this common.  */
       w = XCNEW (struct written_common);
-      w->name = p->name;
+      w->name = lname;
       w->label = label;
       gfc_insert_bbt (&written_commons, w, compare_written_commons);
     }
Index: gcc/testsuite/gfortran.dg/module_commons_3.f90
===================================================================
--- gcc/testsuite/gfortran.dg/module_commons_3.f90	(revision 0)
+++ gcc/testsuite/gfortran.dg/module_commons_3.f90	(revision 0)
@@ -0,0 +1,57 @@
+! { dg-do run }
+!
+! PR fortran/38657, in which the mixture of PRIVATE and
+! COMMON in TEST4, would mess up the association with
+! TESTCHAR in TEST2.
+!
+! Contributed by Paul Thomas <pault@gcc.gnu.org>
+! From a report in clf by Chris Bradley.
+!
+MODULE TEST4
+  PRIVATE
+  CHARACTER(LEN=80) :: T1 = &
+    "Mary had a little lamb, Its fleece was white as snow;"
+  CHARACTER(LEN=80) :: T2 = &
+    "And everywhere that Mary went, The lamb was sure to go."
+  CHARACTER(LEN=80) :: TESTCHAR
+  COMMON /TESTCOMMON1/ TESTCHAR
+  PUBLIC T1, T2, FOOBAR
+CONTAINS
+  subroutine FOOBAR (CHECK)
+    CHARACTER(LEN=80) :: CHECK
+    IF (TESTCHAR .NE. CHECK) CALL ABORT
+  end subroutine
+END MODULE TEST4
+
+MODULE TEST3
+  CHARACTER(LEN=80) :: TESTCHAR
+  COMMON /TESTCOMMON1/ TESTCHAR
+END MODULE TEST3
+
+MODULE TEST2
+  use TEST4
+  USE TEST3, chr => testchar
+  PRIVATE
+  CHARACTER(LEN=80) :: TESTCHAR
+  COMMON /TESTCOMMON1/ TESTCHAR
+  PUBLIC TESTCHAR, FOO, BAR, CHR, T1, T2, FOOBAR
+contains
+  subroutine FOO
+    TESTCHAR = T1
+  end subroutine
+  subroutine BAR (CHECK)
+    CHARACTER(LEN=80) :: CHECK
+    IF (TESTCHAR .NE. CHECK) CALL ABORT
+    IF (CHR .NE. CHECK) CALL ABORT
+  end subroutine
+END MODULE TEST2
+
+PROGRAM TEST1
+  USE TEST2
+  call FOO
+  call BAR (T1)
+  TESTCHAR = T2
+  call BAR (T2)
+  CALL FOOBAR (T2)
+END PROGRAM TEST1
+! { dg-final { cleanup-modules "TEST2 TEST3 TEST4" } }