diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1031a436aa8..88fb3b4b2b5 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2017-01-04  Alexandre Oliva <aoliva@redhat.com>
+
+	* df-scan.c (df_ref_create_structure): Make regno unsigned,
+	to match the caller.
+
 2017-01-04  Alexandre Oliva <aoliva@redhat.com>
 
 	* cfgexpand.c (expand_gimple_basic_block): Disregard debug
diff --git a/gcc/df-scan.c b/gcc/df-scan.c
index ff9d5470015..f75098c2bec 100644
--- a/gcc/df-scan.c
+++ b/gcc/df-scan.c
@@ -2483,7 +2483,7 @@ df_ref_create_structure (enum df_ref_class cl,
 			 int ref_flags)
 {
   df_ref this_ref = NULL;
-  int regno = REGNO (GET_CODE (reg) == SUBREG ? SUBREG_REG (reg) : reg);
+  unsigned int regno = REGNO (GET_CODE (reg) == SUBREG ? SUBREG_REG (reg) : reg);
   struct df_scan_problem_data *problem_data
     = (struct df_scan_problem_data *) df_scan->problem_data;