diff --git a/config_templates/system_settings.ini b/config_templates/system_settings.ini
index 32cebc036..5b6edd8ed 100644
--- a/config_templates/system_settings.ini
+++ b/config_templates/system_settings.ini
@@ -26,6 +26,9 @@
 ; Enable reading the CAL0 partition for HBL.
 ; This is probably undesirable for normal usage.
 ; enable_hbl_cal_read = u8!0x0
+; Disable CAL0 write-protection
+; This is almost certainly undesirable and dangerous for normal usage
+; disable_cal_write = u8!0x0 WARRANTY VOID IF CHANGED - YOU HAVE BEEN WARNED
 ; Controls whether fs.mitm should redirect save files
 ; to directories on the sd card.
 ; 0 = Do not redirect, 1 = Redirect.
diff --git a/stratosphere/ams_mitm/source/fs_mitm/fs_mitm_service.cpp b/stratosphere/ams_mitm/source/fs_mitm/fs_mitm_service.cpp
index 8c13c3f70..ba0c64739 100644
--- a/stratosphere/ams_mitm/source/fs_mitm/fs_mitm_service.cpp
+++ b/stratosphere/ams_mitm/source/fs_mitm/fs_mitm_service.cpp
@@ -251,6 +251,7 @@ namespace ams::mitm::fs {
 
         const bool is_sysmodule = ncm::IsSystemProgramId(this->client_info.program_id);
         const bool is_hbl = this->client_info.override_status.IsHbl();
+        const bool cal_write_protect = !GetSettingsItemBooleanValue("atmosphere", "disable_cal_write");
         const bool can_write_bis = is_sysmodule || (is_hbl && GetSettingsItemBooleanValue("atmosphere", "enable_hbl_bis_write"));
         const bool can_read_cal  = is_sysmodule || (is_hbl && GetSettingsItemBooleanValue("atmosphere", "enable_hbl_cal_read"));
 
@@ -266,8 +267,11 @@ namespace ams::mitm::fs {
             out.SetValue(std::make_shared<IStorageInterface>(new Boot0Storage(bis_storage, this->client_info)), target_object_id);
         } else if (bis_partition_id == FsBisPartitionId_CalibrationBinary) {
             /* PRODINFO should *never* be writable. */
+            if (!cal_write_protect) {
+                /* unless the user explicitly disabled write-protection */
+                out.SetValue(std::make_shared<IStorageInterface>(new RemoteStorage(bis_storage)), target_object_id);
             /* If we have permissions, create a read only storage. */
-            if (can_read_cal) {
+            } else if (can_read_cal) {
                 out.SetValue(std::make_shared<IStorageInterface>(new ReadOnlyStorageAdapter(new RemoteStorage(bis_storage))), target_object_id);
             } else {
                 /* If we can't read cal, return permission denied. */
diff --git a/stratosphere/ams_mitm/source/set_mitm/settings_sd_kvs.cpp b/stratosphere/ams_mitm/source/set_mitm/settings_sd_kvs.cpp
index 7e211a945..bd41a7b82 100644
--- a/stratosphere/ams_mitm/source/set_mitm/settings_sd_kvs.cpp
+++ b/stratosphere/ams_mitm/source/set_mitm/settings_sd_kvs.cpp
@@ -332,6 +332,10 @@ namespace ams::settings::fwdbg {
             /* This is probably undesirable for normal usage. */
             R_ABORT_UNLESS(ParseSettingsItemValue("atmosphere", "enable_hbl_cal_read", "u8!0x0"));
 
+            /* Disable CAL0 write-protection */
+            /* This is almost certainly undesirable and dangerous for normal usage. */
+            R_ABORT_UNLESS(ParseSettingsItemValue("atmosphere", "disable_cal_write", "u8!0x0"));
+
             /* Controls whether dmnt cheats should be toggled on or off by */
             /* default. 1 = toggled on by default, 0 = toggled off by default. */
             R_ABORT_UNLESS(ParseSettingsItemValue("atmosphere", "dmnt_cheats_enabled_by_default", "u8!0x1"));