diff --git a/gcc/ada/libgnarl/s-inmaop__posix.adb b/gcc/ada/libgnarl/s-inmaop__posix.adb
index 3171399f982da3334c4378f825552b7344062e9c..e4d07ee77eb4807fbb840db1dd03b5b130c9c1e4 100644
--- a/gcc/ada/libgnarl/s-inmaop__posix.adb
+++ b/gcc/ada/libgnarl/s-inmaop__posix.adb
@@ -135,6 +135,7 @@ package body System.Interrupt_Management.Operations is
 
    begin
       Result := sigwait (Mask, Sig'Access);
+      pragma Assert (Result = 0);
 
       if Result /= 0 then
          return 0;