--- gcc/ada/freeze.adb
+++ gcc/ada/freeze.adb
@@ -3569,7 +3569,8 @@ package body Freeze is
             Error_Msg_N ("\??use explicit size clause to set size", E);
          end if;
 
-         if Is_Array_Type (Typ) then
+         --  Declaring a too-big array in disabled ghost code is OK
+         if Is_Array_Type (Typ) and then not Is_Ignored_Ghost_Entity (E) then
             Check_Large_Modular_Array (Typ);
          end if;
       end Freeze_Object_Declaration;

--- /dev/null
new file mode 100644
+++ gcc/testsuite/gnat.dg/ghost7.adb
@@ -0,0 +1,6 @@
+--  { dg-do compile }
+--  { dg-options "-gnatwa" }
+
+package body Ghost7 is
+   procedure Dummy is null;
+end Ghost7;

--- /dev/null
new file mode 100644
+++ gcc/testsuite/gnat.dg/ghost7.ads
@@ -0,0 +1,8 @@
+pragma Restrictions (No_Exception_Propagation);
+
+package Ghost7 is
+   type Word64 is mod 2**64;
+   type My_Array_Type is array (Word64) of Boolean;
+   My_Array : My_Array_Type with Ghost;
+   procedure Dummy;
+end Ghost7;
\ No newline at end of file