diff --git a/core/ISmmAPI.h b/core/ISmmAPI.h
index 65a01fd..9fc37a3 100644
--- a/core/ISmmAPI.h
+++ b/core/ISmmAPI.h
@@ -39,7 +39,6 @@
 
 #if defined META_NO_HL2SDK
 class CGlobalVars;
-class IServerPluginCallbacks;
 struct edict_t;
 class ConCommandBase;
 #else
@@ -62,6 +61,8 @@ class ConCommandBase;
 
 typedef void* (*CreateInterfaceFn)(const char *pName, int *pReturnCode);
 
+class IServerPluginCallbacks;
+
 namespace SourceMM
 {
 	class ISmmPlugin;
diff --git a/core/ISmmPlugin.h b/core/ISmmPlugin.h
index 12a0665..6b11732 100644
--- a/core/ISmmPlugin.h
+++ b/core/ISmmPlugin.h
@@ -39,6 +39,8 @@
 #include <ISmmAPI.h>
 #include <ISmmPluginExt.h>
 
+class IServerPluginCallbacks;
+
 // Interface return status, binary-compatible with HL2SDK's IFACE_OK and IFACE_FAILED.
 enum 
 {
diff --git a/core/provider/provider_ep2.cpp b/core/provider/provider_ep2.cpp
index 86026de..a7904dc 100644
--- a/core/provider/provider_ep2.cpp
+++ b/core/provider/provider_ep2.cpp
@@ -38,6 +38,7 @@
 #include "metamod_console.h"
 #include <filesystem.h>
 #include "metamod.h"
+#include <tier1/KeyValues.h>
 
 #if SOURCE_ENGINE == SE_SOURCE2
 SH_DECL_HOOK1(ISource2ServerConfig, AllowDedicatedServers, const, 0, bool, EUniverse);
diff --git a/core/provider/provider_ep2.h b/core/provider/provider_ep2.h
index 0ac92fd..26dfa89 100644
--- a/core/provider/provider_ep2.h
+++ b/core/provider/provider_ep2.h
@@ -32,7 +32,9 @@
 #endif
 #include <sourcehook.h>
 #include <sh_memfuncinfo.h>
+#if SOURCE_ENGINE != SE_SOURCE2
 #include <iserverplugin.h>
+#endif
 #include "ISmmAPI.h"
 #include "metamod_provider.h"
 #include "metamod_oslink.h"