diff --git a/bfd/hppabsd-core.c b/bfd/hppabsd-core.c
index ae5d1f8f1e5..1c24e641b3a 100644
--- a/bfd/hppabsd-core.c
+++ b/bfd/hppabsd-core.c
@@ -179,7 +179,8 @@ hppabsd_core_core_file_p (bfd *abfd)
     goto fail;
   core_regsec (abfd)->vma = 0;
 
-  strncpy (core_command (abfd), u.u_comm, MAXCOMLEN + 1);
+  strncpy (core_command (abfd), u.u_comm, MAXCOMLEN);
+  core_command (abfd)[MAXCOMLEN] = 0;
   core_signal (abfd) = u.u_code;
   return _bfd_no_cleanup;
 
diff --git a/bfd/hpux-core.c b/bfd/hpux-core.c
index 1e2ea926f02..18516e3a897 100644
--- a/bfd/hpux-core.c
+++ b/bfd/hpux-core.c
@@ -177,7 +177,8 @@ hpux_core_core_file_p (bfd *abfd)
 	    struct proc_exec proc_exec;
 	    if (bfd_read (&proc_exec, core_header.len, abfd) != core_header.len)
 	      break;
-	    strncpy (core_command (abfd), proc_exec.cmd, MAXCOMLEN + 1);
+	    strncpy (core_command (abfd), proc_exec.cmd, MAXCOMLEN);
+	    core_command (abfd)[MAXCOMLEN] = 0;
 	    good_sections++;
 	  }
 	  break;
diff --git a/bfd/irix-core.c b/bfd/irix-core.c
index 80cb82d0fa3..7a486841d35 100644
--- a/bfd/irix-core.c
+++ b/bfd/irix-core.c
@@ -203,7 +203,8 @@ irix_core_core_file_p (bfd *abfd)
   if (!core_hdr (abfd))
     return NULL;
 
-  strncpy (core_command (abfd), coreout.c_name, CORE_NAMESIZE);
+  strncpy (core_command (abfd), coreout.c_name, CORE_NAMESIZE - 1);
+  core_command (abfd)[CORE_NAMESIZE - 1] = 0;
   core_signal (abfd) = coreout.c_sigcause;
 
   if (bfd_seek (abfd, coreout.c_vmapoffset, SEEK_SET) != 0)
diff --git a/bfd/lynx-core.c b/bfd/lynx-core.c
index 44d94ad8745..7870dc62866 100644
--- a/bfd/lynx-core.c
+++ b/bfd/lynx-core.c
@@ -120,7 +120,8 @@ lynx_core_file_p (bfd *abfd)
   if (!core_hdr (abfd))
     return NULL;
 
-  strncpy (core_command (abfd), pss.pname, PNMLEN + 1);
+  strncpy (core_command (abfd), pss.pname, PNMLEN);
+  core_command (abfd)[PNMLEN] = 0;
 
   /* Compute the size of the thread contexts */
 
diff --git a/bfd/mach-o.c b/bfd/mach-o.c
index 974747caadd..037718fb22c 100644
--- a/bfd/mach-o.c
+++ b/bfd/mach-o.c
@@ -6019,9 +6019,9 @@ bfd_mach_o_core_file_failing_command (bfd *abfd)
   int ret;
 
   ret = bfd_mach_o_core_fetch_environment (abfd, &buf, &len);
-  if (ret < 0)
+  if (ret < 0 || len == 0)
     return NULL;
-
+  buf[len - 1] = 0;
   return (char *) buf;
 }
 
diff --git a/bfd/osf-core.c b/bfd/osf-core.c
index 55b127d48b3..6869dfa23ea 100644
--- a/bfd/osf-core.c
+++ b/bfd/osf-core.c
@@ -92,7 +92,8 @@ osf_core_core_file_p (bfd *abfd)
   if (!core_hdr (abfd))
     return NULL;
 
-  strncpy (core_command (abfd), core_header.name, MAXCOMLEN + 1);
+  strncpy (core_command (abfd), core_header.name, MAXCOMLEN);
+  core_command (abfd)[MAXCOMLEN] = 0;
   core_signal (abfd) = core_header.signo;
 
   for (i = 0; i < core_header.nscns; i++)