diff --git a/src/arch/x86/remote_gdb.hh b/src/arch/x86/remote_gdb.hh
index 4a917925e9..f1cbcbe8c3 100644
--- a/src/arch/x86/remote_gdb.hh
+++ b/src/arch/x86/remote_gdb.hh
@@ -96,7 +96,7 @@ class RemoteGDB : public BaseRemoteGDB
     {
       using BaseGdbRegCache::BaseGdbRegCache;
       private:
-        struct {
+        struct M5_ATTR_PACKED {
           uint64_t rax;
           uint64_t rbx;
           uint64_t rcx;