diff --git a/gcc/ada/exp_ch9.adb b/gcc/ada/exp_ch9.adb
--- a/gcc/ada/exp_ch9.adb
+++ b/gcc/ada/exp_ch9.adb
@@ -2769,6 +2769,21 @@ package body Exp_Ch9 is
             --  Start of processing for Process_Node
 
             begin
+               --  Validity checks are suppressed while an explicitly
+               --  lock-free protected subprogram is analyzed directly.
+               --  When the implementation is selected automatically the
+               --  checks have already been inserted in the original
+               --  statements before they are copied here, so drop those
+               --  stale checks from the generated lock-free body.
+
+               if Nkind (N) = N_Raise_Constraint_Error
+                 and then RT_Exception_Code'Val (UI_To_Int (Reason (N))) =
+                            CE_Invalid_Data
+               then
+                  Rewrite (N, Make_Null_Statement (Sloc (N)));
+                  return Skip;
+               end if;
+
                --  Wrap each return and raise statement that appear inside a
                --  procedure. Skip the last return statement which is added by
                --  default since it is transformed into an exit statement.
diff --git a/gcc/testsuite/gnat.dg/protected_duration_validity.adb b/gcc/testsuite/gnat.dg/protected_duration_validity.adb
new file mode 100644
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/protected_duration_validity.adb
@@ -0,0 +1,31 @@
+--  { dg-do run }
+--  { dg-options "-O2 -gnatVa" }
+
+with Ada.Text_IO; use Ada.Text_IO;
+
+procedure Protected_Duration_Validity is
+   protected Control is
+      procedure Set (Value : Duration);
+      function Get return Duration;
+   private
+      Current : Duration := 0.0;
+   end Control;
+
+   protected body Control is
+      procedure Set (Value : Duration) is
+      begin
+         Current := Value;
+      end Set;
+
+      function Get return Duration is
+      begin
+         return Current;
+      end Get;
+   end Control;
+begin
+   Control.Set (-1.0);
+   if Control.Get /= -1.0 then
+      raise Program_Error with "protected Duration round trip failed";
+   end if;
+   Put_Line ("PASS protected Duration validity");
+end Protected_Duration_Validity;