diff --git a/rpcs3/Emu/Cell/Modules/sceNpTrophy.cpp b/rpcs3/Emu/Cell/Modules/sceNpTrophy.cpp
index 8e07340622..990ef2aef5 100644
--- a/rpcs3/Emu/Cell/Modules/sceNpTrophy.cpp
+++ b/rpcs3/Emu/Cell/Modules/sceNpTrophy.cpp
@@ -819,9 +819,19 @@ error_code sceNpTrophyUnlockTrophy(u32 context, u32 handle, s32 trophyId, vm::pt
 	}
 
 	if (trophyId < 0 || trophyId >= static_cast<s32>(ctxt->tropusr->GetTrophiesCount()))
+	{
 		return SCE_NP_TROPHY_ERROR_INVALID_TROPHY_ID;
+	}
+
+	if (ctxt->tropusr->GetTrophyGrade(trophyId) == SCE_NP_TROPHY_GRADE_PLATINUM)
+	{
+		return SCE_NP_TROPHY_ERROR_CANNOT_UNLOCK_PLATINUM;
+	}
+
 	if (ctxt->tropusr->GetTrophyUnlockState(trophyId))
+	{
 		return SCE_NP_TROPHY_ERROR_ALREADY_UNLOCKED;
+	}
 
 	ctxt->tropusr->UnlockTrophy(trophyId, 0, 0); // TODO: add timestamps
 
diff --git a/rpcs3/Loader/TROPUSR.cpp b/rpcs3/Loader/TROPUSR.cpp
index 7a57df8b54..60d79d235a 100644
--- a/rpcs3/Loader/TROPUSR.cpp
+++ b/rpcs3/Loader/TROPUSR.cpp
@@ -291,6 +291,17 @@ u32 TROPUSRLoader::GetUnlockedPlatinumID(u32 trophy_id, const std::string& confi
 	return pid;
 }
 
+u32 TROPUSRLoader::GetTrophyGrade(u32 id)
+{
+	if (id >= m_table4.size())
+	{
+		LOG_WARNING(LOADER, "TROPUSRLoader::GetTrophyGrade: Invalid id=%d", id);
+		return trophy_grade::unknown;
+	}
+
+	return m_table4[id].trophy_grade; // Let's assume the trophies are stored ordered
+}
+
 u32 TROPUSRLoader::GetTrophyUnlockState(u32 id)
 {
 	if (id >= m_table6.size())
diff --git a/rpcs3/Loader/TROPUSR.h b/rpcs3/Loader/TROPUSR.h
index 5e5b037b52..2ecc92238e 100644
--- a/rpcs3/Loader/TROPUSR.h
+++ b/rpcs3/Loader/TROPUSR.h
@@ -86,6 +86,7 @@ public:
 
 	virtual u32 GetUnlockedPlatinumID(u32 trophy_id, const std::string& config_path);
 
+	virtual u32 GetTrophyGrade(u32 id);
 	virtual u32 GetTrophyUnlockState(u32 id);
 	virtual u64 GetTrophyTimestamp(u32 id);