diff --git a/dlls/ntoskrnl.exe/instr.c b/dlls/ntoskrnl.exe/instr.c
index 68140c09ef7..44f2ed4f515 100644
--- a/dlls/ntoskrnl.exe/instr.c
+++ b/dlls/ntoskrnl.exe/instr.c
@@ -815,7 +815,11 @@ static DWORD emulate_instruction( EXCEPTION_RECORD *rec, CONTEXT *context )
                 context->Rax = (ULONG)syscall_address;
                 break;
             }
-            default: return ExceptionContinueSearch;
+            default:
+                FIXME("reg %#x, returning 0.\n", reg);
+                context->Rdx = 0;
+                context->Rax = 0;
+                break;
             }
             context->Rip += prefixlen + 2;
             return ExceptionContinueExecution;