diff --git a/core/ConVarManager.cpp b/core/ConVarManager.cpp
index f32c9a20..04aa6416 100644
--- a/core/ConVarManager.cpp
+++ b/core/ConVarManager.cpp
@@ -182,7 +182,7 @@ void ConVarManager::OnSourceModVSPReceived()
 	}
 
 	/* For later MM:S versions, use the updated API, since it's cleaner. */
-#if defined METAMOD_PLAPI_VERSION
+#if defined METAMOD_PLAPI_VERSION || PLAPI_VERSION >= 11
 	int engine = g_SMAPI->GetSourceEngineBuild();
 	if (engine == SOURCE_ENGINE_ORIGINAL || vsp_version < 2)
 	{
diff --git a/core/HalfLife2.cpp b/core/HalfLife2.cpp
index e7432118..d9c6e88c 100644
--- a/core/HalfLife2.cpp
+++ b/core/HalfLife2.cpp
@@ -96,14 +96,16 @@ CHalfLife2::~CHalfLife2()
 CSharedEdictChangeInfo *g_pSharedChangeInfo = NULL;
 #endif
 
+#if !defined METAMOD_PLAPI_VERSION || PLAPI_VERSION < 11
 bool is_original_engine = false;
+#endif
 
 void CHalfLife2::OnSourceModStartup(bool late)
 {
 #if SOURCE_ENGINE != SE_DARKMESSIAH
 
 	/* The Ship currently is the only known game to use an older version of the engine */
-#if defined METAMOD_PLAPI_VERSION
+#if defined METAMOD_PLAPI_VERSION || PLAPI_VERSION >= 11
 	if (g_SMAPI->GetSourceEngineBuild() == SOURCE_ENGINE_ORIGINAL)
 #else
 	if (strcasecmp(g_SourceMod.GetGameFolderName(), "ship") == 0)
@@ -172,7 +174,7 @@ void CHalfLife2::OnSourceModAllInitialized_Post()
 	}
 }
 
-#if !defined METAMOD_PLAPI_VERSION
+#if !defined METAMOD_PLAPI_VERSION || PLAPI_VERSION < 11
 bool CHalfLife2::IsOriginalEngine()
 {
 	return is_original_engine;
@@ -543,7 +545,7 @@ bool CHalfLife2::IsLANServer()
 
 bool CHalfLife2::KVLoadFromFile(KeyValues *kv, IBaseFileSystem *filesystem, const char *resourceName, const char *pathID)
 {
-#if defined METAMOD_PLAPI_VERSION
+#if defined METAMOD_PLAPI_VERSION || PLAPI_VERSION >= 11
 	if (g_SMAPI->GetSourceEngineBuild() == SOURCE_ENGINE_ORIGINAL)
 #else
 	if (strcasecmp(g_SourceMod.GetGameFolderName(), "ship") == 0)
diff --git a/core/HalfLife2.h b/core/HalfLife2.h
index f42a40ee..1cceaba0 100644
--- a/core/HalfLife2.h
+++ b/core/HalfLife2.h
@@ -145,7 +145,7 @@ public:
 	const char *CurrentCommandName();
 	void AddDelayedKick(int client, int userid, const char *msg);
 	void ProcessDelayedKicks();
-#if !defined METAMOD_PLAPI_VERSION
+#if !defined METAMOD_PLAPI_VERSION || PLAPI_VERSION < 11
 	bool IsOriginalEngine();
 #endif
 private:
diff --git a/core/smn_halflife.cpp b/core/smn_halflife.cpp
index 0e98237d..e02aa9f6 100644
--- a/core/smn_halflife.cpp
+++ b/core/smn_halflife.cpp
@@ -438,28 +438,25 @@ static cell_t smn_IsPlayerAlive(IPluginContext *pContext, const cell_t *params)
 
 static cell_t GuessSDKVersion(IPluginContext *pContext, const cell_t *params)
 {
-#if defined METAMOD_PLAPI_VERSION
+#if defined METAMOD_PLAPI_VERSION || PLAPI_VERSION >= 11
 	int version = g_SMAPI->GetSourceEngineBuild();
 
-	if (version == SOURCE_ENGINE_ORIGINAL)
+	switch (version)
 	{
+	case SOURCE_ENGINE_ORIGINAL:
 		return 10;
-	}
-	else if (version == SOURCE_ENGINE_DARKMESSIAH)
-	{
-		return 15;
-	}
-	else if (version == SOURCE_ENGINE_EPISODEONE)
-	{
+	case SOURCE_ENGINE_EPISODEONE:
 		return 20;
-	}
-	else if (version == SOURCE_ENGINE_ORANGEBOX)
-	{
+
+# if defined METAMOD_PLAPI_VERISON
+	/* Newer games. */
+	case SOURCE_ENGINE_DARKMESSIAH:
+		return 15;
+	case SOURCE_ENGINE_ORANGEBOX:
 		return 30;
-	}
-	else if (version == SOURCE_ENGINE_LEFT4DEAD)
-	{
+	case SOURCE_ENGINE_LEFT4DEAD:
 		return 40;
+# endif
 	}
 #else
 	if (g_HL2.IsOriginalEngine())