diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 6ebc9bedb63..185d4a37e04 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,7 @@
+2020-10-30  Simon Marchi  <simon.marchi@polymtl.ca>
+
+	* rs6000-tdep.c (rs6000_dwarf2_reg_to_regnum): Return -1 for
+
 2020-10-30  Tom Tromey  <tromey@adacore.com>
 
 	* Makefile.in (stamp-init): Depend on config.status.
diff --git a/gdb/rs6000-tdep.c b/gdb/rs6000-tdep.c
index 264d4e03e7f..4b8c3ed99ca 100644
--- a/gdb/rs6000-tdep.c
+++ b/gdb/rs6000-tdep.c
@@ -3240,9 +3240,10 @@ rs6000_dwarf2_reg_to_regnum (struct gdbarch *gdbarch, int num)
         return tdep->ppc_vrsave_regnum;
       case 612:
         return tdep->ppc_spefscr_regnum;
-      default:
-        return num;
       }
+
+  /* Unknown DWARF register number.  */
+  return -1;
 }
 
 /* Translate a .eh_frame register to DWARF register, or adjust a