diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index d9b75725257..bd3450fffd1 100644
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -1,3 +1,9 @@
+2019-08-13  Ed Schonberg  <schonberg@adacore.com>
+
+	* sem_ch8.adb (Analyze_Subprogram_Renaming): Do no suppress mode
+	conformance checks on child unit instance that is a compilation
+	unit.
+
 2019-08-13  Gary Dismukes  <dismukes@adacore.com>
 
 	* exp_dbug.adb (Fully_Qualify_Name): Add full name qualification
diff --git a/gcc/ada/sem_ch8.adb b/gcc/ada/sem_ch8.adb
index 8795dc07f95..38c3980278d 100644
--- a/gcc/ada/sem_ch8.adb
+++ b/gcc/ada/sem_ch8.adb
@@ -3368,7 +3368,16 @@ package body Sem_Ch8 is
 
             if CW_Actual then
                null;
-            elsif not Is_Actual or else No (Enclosing_Instance) then
+
+            --  No need for a redundant error message if this is a nested
+            --  instance, unless the current instantiation (of a child unit)
+            --  is a compilation unit, which is not analyzed when the parent
+            --  generic is analyzed.
+
+            elsif not Is_Actual
+               or else No (Enclosing_Instance)
+               or else Is_Compilation_Unit (Current_Scope)
+            then
                Check_Mode_Conformant (New_S, Old_S);
             end if;