diff --git a/Core/System.cpp b/Core/System.cpp
index 73606e9c08..fb7e378e69 100644
--- a/Core/System.cpp
+++ b/Core/System.cpp
@@ -878,6 +878,18 @@ bool PSP_InitStart(const CoreParameter &coreParam) {
 			}
 		}
 
+		if (filename.GetFilename() == "vshmain.prx") {
+			// A firmware installed for the other model makes the XMB look for files it doesn't have.
+			InstalledFirmwareInfo firmware;
+			ReadInstalledFirmwareInfo(g_Config.nandRootDirectory, &firmware, false);
+			if (!InstalledFirmwareFitsModel(firmware, g_Config.iPSPModel)) {
+				auto sy = GetI18NCategory(I18NCat::SYSTEM);
+				g_OSD.Show(OSDType::MESSAGE_WARNING, ApplySafeSubstitutions(
+					sy->T("FirmwareOtherModel", "Firmware %1 was installed for a different PSP model, so the XMB may not work. Install it again for this model."),
+					firmware.version), 10.0f, "firmware_model");
+			}
+		}
+
 		if (System_GetPropertyBool(SYSPROP_ENOUGH_RAM_FOR_FULL_ISO)) {
 			if (g_Config.bCacheFullIsoInRam) {
 				switch (fileType) {
diff --git a/Core/Util/PSARUnpack.cpp b/Core/Util/PSARUnpack.cpp
index c5b5e44ac2..44da1af5c7 100644
--- a/Core/Util/PSARUnpack.cpp
+++ b/Core/Util/PSARUnpack.cpp
@@ -1323,6 +1323,31 @@ void ReadInstalledFirmwareInfo(const Path &nandRoot, InstalledFirmwareInfo *info
 	if (File::ReadTextFileToString(flash0 / "vsh/etc/version.txt", &versionTxt)) {
 		ParseVersionTxt(versionTxt, info);
 	}
+
+	// 3.x names them nandipl_psp1000.bin and nandipl_psp2000.ipl (psp02h in 4.x), 5.x on nandipl_01g.bin
+	// and so on. Older firmwares have one psp_ipl.bin or psp_nandipl.bin for every model.
+	std::vector<File::FileInfo> ipls;
+	File::GetFilesInDir(nandRoot / "ipl", &ipls);
+	bool anyModelTagged = false;
+	for (const File::FileInfo &ipl : ipls) {
+		const std::string name = ipl.name;
+		const bool for1000 = name.find("psp1000") != std::string::npos || name.find("_01g") != std::string::npos;
+		const bool for2000 = name.find("psp2000") != std::string::npos || name.find("psp02h") != std::string::npos || name.find("_02g") != std::string::npos;
+		info->forPSP1000 |= for1000;
+		info->forPSP2000 |= for2000;
+		anyModelTagged |= for1000 || for2000 || name.find("g.") != std::string::npos;
+	}
+	if (!anyModelTagged) {
+		info->forPSP1000 = true;
+		info->forPSP2000 = true;
+	}
+}
+
+bool InstalledFirmwareFitsModel(const InstalledFirmwareInfo &info, int pspModel) {
+	if (!info.hasVsh) {
+		return true;
+	}
+	return pspModel == PSP_MODEL_FAT ? info.forPSP1000 : info.forPSP2000;
 }
 
 bool EraseInstalledFirmware(const Path &nandRoot, std::string *error) {
diff --git a/Core/Util/PSARUnpack.h b/Core/Util/PSARUnpack.h
index 0d07e2c9de..8535a48794 100644
--- a/Core/Util/PSARUnpack.h
+++ b/Core/Util/PSARUnpack.h
@@ -163,6 +163,11 @@ struct InstalledFirmwareInfo {
 	int kernelModuleCount = 0;       // Files in flash0:/kd, which is what --disable-hle wants.
 	int fileCount = 0;
 	u64 totalSize = 0;
+	// Which of the models we emulate the install has files for, from the names of its ipl/ files
+	// ("nandipl_01g.bin", "nandipl_psp2000.ipl"). An install for every model has both, and so does
+	// a firmware from before the PSP-2000, whose one ipl serves every model.
+	bool forPSP1000 = false;
+	bool forPSP2000 = false;
 };
 
 // Walks the NAND directory (the one holding flash0/flash1). Pass countFiles = false when
@@ -170,6 +175,10 @@ struct InstalledFirmwareInfo {
 // and a full firmware is a few hundred files, which isn't free on a phone's storage.
 void ReadInstalledFirmwareInfo(const Path &nandRoot, InstalledFirmwareInfo *info, bool countFiles = true);
 
+// False if a full firmware is installed and has no files for pspModel (PSP_MODEL_*). Its XMB then
+// looks for the other model's files, which aren't there.
+bool InstalledFirmwareFitsModel(const InstalledFirmwareInfo &info, int pspModel);
+
 // Wipes what's in the NAND directory: flash0, flash1 and ipl. Two firmwares can't be merged -
 // files a newer one dropped would linger and still get loaded - so an install starts from empty.
 // Deliberately leaves an install's staging directory alone: InstallFirmware() calls this with a
diff --git a/UI/Settings/SystemPage.cpp b/UI/Settings/SystemPage.cpp
index dad32cb3ec..99e469cf9b 100644
--- a/UI/Settings/SystemPage.cpp
+++ b/UI/Settings/SystemPage.cpp
@@ -26,6 +26,7 @@
 #include "Common/Data/Text/I18n.h"
 #include "Common/File/FileUtil.h"
 #include "Common/File/Path.h"
+#include "Common/StringUtils.h"
 #include "Common/GPU/thin3d.h"
 #include "Common/Log.h"
 #include "Common/Render/ManagedTexture.h"
@@ -44,6 +45,7 @@
 #include "Core/Reporting.h"
 #include "Core/System.h"
 #include "Core/Util/PathUtil.h"
+#include "Core/Util/PSARUnpack.h"
 #include "UI/Background.h"
 #include "UI/GameSettingsScreen.h"
 #include "UI/MemStickScreen.h"
@@ -173,6 +175,31 @@ static void OnJitAffectingSetting() {
 	System_PostUIMessage(UIMessage::REQUEST_CLEAR_JIT);
 }
 
+// A firmware only has the files of the model it was installed for, and its XMB looks for the files of
+// the model we report. So a change to a model the installed firmware doesn't fit gets a warning.
+static void OnPSPModelChanged(SettingsPageHost *host, int previous) {
+	if (g_Config.iPSPModel == previous) {
+		return;
+	}
+	InstalledFirmwareInfo firmware;
+	ReadInstalledFirmwareInfo(GetSysDirectory(DIRECTORY_NAND), &firmware, false);
+	if (InstalledFirmwareFitsModel(firmware, g_Config.iPSPModel)) {
+		return;
+	}
+	auto di = GetI18NCategory(I18NCat::DIALOG);
+	auto sy = GetI18NCategory(I18NCat::SYSTEM);
+	const std::string message = ApplySafeSubstitutions(
+		sy->T("FirmwareModelChange", "Firmware %1 is installed for a different PSP model. With this one, the XMB may not work until you install the firmware again."),
+		firmware.version);
+	host->PageScreenManager()->push(new UI::MessagePopupScreen(sy->T("PSP Model"), message, di->T("OK"), di->T("Cancel"), [host, previous](bool yes) {
+		if (!yes) {
+			g_Config.iPSPModel = previous;
+		}
+		// Either way, so the next change compares against the model now set.
+		host->RecreatePageViews();
+	}));
+}
+
 // Using SYSTEM translations
 static void BuildPSPSettingsPage(SettingsPage *page) {
 	SettingsPageHost *host = page->Host();
@@ -181,8 +208,11 @@ static void BuildPSPSettingsPage(SettingsPage *page) {
 
 	// The ordering here is simply mapping directly to PSP_SYSTEMPARAM_LANGUAGE_*.
 	page->Setting(&g_Config.iLanguage);
+	const int modelShown = g_Config.iPSPModel;
 	page->Setting(&g_Config.iPSPModel).EnabledFunc([] {
 		return !PSP_IsInited();
+	}).OnChange([host, modelShown](UI::EventParams &) {
+		OnPSPModelChanged(host, modelShown);
 	});
 	page->Custom("Nickname", [host](UI::ViewGroup *parent) {
 		return AddNicknameChoice(host, parent);
diff --git a/assets/lang/en_US.ini b/assets/lang/en_US.ini
index 15fd5e9fb3..377cb41fc6 100644
--- a/assets/lang/en_US.ini
+++ b/assets/lang/en_US.ini
@@ -1631,7 +1631,9 @@ Files = Files
 Final processed image = Final processed image
 Firmware installation failed = Firmware installation failed
 Firmware version = Firmware version
+FirmwareModelChange = Firmware %1 is installed for a different PSP model. With this one, the XMB may not work until you install the firmware again.
 FirmwareNeedsNoGame = Stop the game to change the installed firmware
+FirmwareOtherModel = Firmware %1 was installed for a different PSP model, so the XMB may not work. Install it again for this model.
 FirmwareSources = PPSSPP has its own replacements for the PSP's system files, so a firmware is optional. Installing one gets you the real fonts, and lets you launch the XMB. Most game discs carry a firmware updater - open a game's info screen to install from it.
 Fonts = Fonts
 Grid = Grid