diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index 9af9fab6135..e51a2a30833 100644
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -1,3 +1,9 @@
+2018-09-24  Eric Botcazou  <ebotcazou@adacore.com>
+
+	PR ada/87396
+	* fe.h (Get_Attribute_Definition_Clause): Use 'unsigned char' instead
+	of 'char' as the type of the second parameter.
+
 2018-09-13  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* Makefile.rtl (arm% linux-gnueabi%): Always set EH_MECHANISM to -arm.
diff --git a/gcc/ada/fe.h b/gcc/ada/fe.h
index 1928609ba05..2d07aa506c7 100644
--- a/gcc/ada/fe.h
+++ b/gcc/ada/fe.h
@@ -85,7 +85,7 @@ extern void Set_RM_Size			(Entity_Id, Uint);
 extern Boolean Is_Entity_Name		(Node_Id);
 
 #define Get_Attribute_Definition_Clause einfo__get_attribute_definition_clause
-extern Node_Id Get_Attribute_Definition_Clause (Entity_Id, char);
+extern Node_Id Get_Attribute_Definition_Clause (Entity_Id, unsigned char);
 
 /* errout: */