diff --git a/thermosphere/src/gdb/hvisor_gdb_defines_internal.hpp b/thermosphere/src/gdb/hvisor_gdb_defines_internal.hpp
index 4bfc7e6cf..453079a80 100644
--- a/thermosphere/src/gdb/hvisor_gdb_defines_internal.hpp
+++ b/thermosphere/src/gdb/hvisor_gdb_defines_internal.hpp
@@ -30,17 +30,19 @@
 // IDA seems to want additional bytes as well.
 // 1024 is fine enough to put all regs in the 'T' stop reply packets
 // Add 4 to this for the actual allocated size, for $#<checksum>, see below.
-#define GDB_BUF_LEN 0x800
-#define GDB_WORK_BUF_LEN 0x1000
+#define GDB_BUF_LEN                                 0x800
+#define GDB_WORK_BUF_LEN                            0x1000
 
-#define GDB_HANDLER(name)                   Handle##name
-#define GDB_QUERY_HANDLER(name)             GDB_HANDLER(Query##name)
-#define GDB_VERBOSE_HANDLER(name)           GDB_HANDLER(Verbose##name)
-#define GDB_REMOTE_COMMAND_HANDLER(name)    GDB_HANDLER(RemoteCommand##name)
-#define GDB_XFER_HANDLER(name)              GDB_HANDLER(Xfer##name)
+#define GDB_HANDLER(name)                           Handle##name
+#define GDB_QUERY_HANDLER(name)                     GDB_HANDLER(Query##name)
+#define GDB_VERBOSE_HANDLER(name)                   GDB_HANDLER(Verbose##name)
+#define GDB_REMOTE_COMMAND_HANDLER(name)            GDB_HANDLER(RemoteCommand##name)
+#define GDB_XFER_HANDLER(name)                      GDB_HANDLER(Xfer##name)
 
 #define GDB_DEFINE_HANDLER(name)                    int Context::GDB_HANDLER(name)()
 #define GDB_DEFINE_QUERY_HANDLER(name)              GDB_DEFINE_HANDLER(Query##name)
 #define GDB_DEFINE_VERBOSE_HANDLER(name)            GDB_DEFINE_HANDLER(Verbose##name)
 #define GDB_DEFINE_REMOTE_COMMAND_HANDLER(name)     GDB_DEFINE_HANDLER(RemoteCommand##name)
 #define GDB_DECLARE_XFER_HANDLER(name)              GDB_DEFINE_HANDLER(Xfer##name)
+
+#define GDB_TEST_NO_CMD_DATA()                      do { if (!m_commandData.empty()) return ReplyErrno(EILSEQ); } while (false)
diff --git a/thermosphere/src/gdb/hvisor_gdb_regs.cpp b/thermosphere/src/gdb/hvisor_gdb_regs.cpp
index f6b70c613..5efc61165 100644
--- a/thermosphere/src/gdb/hvisor_gdb_regs.cpp
+++ b/thermosphere/src/gdb/hvisor_gdb_regs.cpp
@@ -75,6 +75,7 @@ namespace ams::hvisor::gdb {
     GDB_DEFINE_HANDLER(ReadRegisters)
     {
         ENSURE(m_selectedCoreId == currentCoreCtx->coreId);
+        GDB_TEST_NO_CMD_DATA();
 
         ExceptionStackFrame *frame = currentCoreCtx->guestFrame;
         FpuRegisterCache *fpuRegCache = fpuReadRegisters();
diff --git a/thermosphere/src/gdb/hvisor_gdb_thread.cpp b/thermosphere/src/gdb/hvisor_gdb_thread.cpp
index abde4d81e..6873d2d47 100644
--- a/thermosphere/src/gdb/hvisor_gdb_thread.cpp
+++ b/thermosphere/src/gdb/hvisor_gdb_thread.cpp
@@ -96,11 +96,14 @@ namespace ams::hvisor::gdb {
 
     GDB_DEFINE_QUERY_HANDLER(CurrentThreadId)
     {
+        GDB_TEST_NO_CMD_DATA();
         return SendFormattedPacket("QC%x", 1 + currentCoreCtx->coreId);
     }
 
     GDB_DEFINE_QUERY_HANDLER(fThreadInfo)
     {
+        GDB_TEST_NO_CMD_DATA();
+
         // We have made our GDB packet big enough to list all the thread ids (coreIds + 1 for each coreId)
         char *buf = GetInPlaceOutputBuffer();
         size_t n = 0;
@@ -117,6 +120,8 @@ namespace ams::hvisor::gdb {
 
     GDB_DEFINE_QUERY_HANDLER(sThreadInfo)
     {
+        GDB_TEST_NO_CMD_DATA();
+
         // We have made our GDB packet big enough to list all the thread ids (coreIds + 1 for each coreId) in fThreadInfo
         // Note: we assume GDB doesn't accept notifications during the sequence transfer...
         return SendPacket("l");