diff --git a/core/ISmmAPI.h b/core/ISmmAPI.h
index ef5ed9f..f9c916d 100644
--- a/core/ISmmAPI.h
+++ b/core/ISmmAPI.h
@@ -34,8 +34,6 @@
  */
 
 #include <stdarg.h>
-#include <interface.h>
-#include <eiface.h>
 #include <sourcehook.h>
 #include <IPluginManager.h>
 #include <ISmmPlugin.h>
@@ -52,6 +50,24 @@
 #define MMIFACE_SH_HOOKMANAUTOGEN	"IHookManagerAutoGen"		/**< SourceHook::IHookManagerAutoGen Pointer */
 #define IFACE_MAXNUM			999						/**< Maximum interface version */
 
+#if defined META_NO_HL2SDK
+class CGlobalVars;
+class IServerPluginCallbacks;
+struct edict_t;
+class ConCommandBase;
+#else
+#include <eiface.h>
+#endif
+
+// Interface return status, binary-compatible with HL2SDK's IFACE_OK and IFACE_FAILED.
+enum 
+{
+	META_IFACE_OK = 0,
+	META_IFACE_FAILED
+};
+
+typedef void* (*CreateInterfaceFn)(const char *pName, int *pReturnCode);
+
 namespace SourceMM
 {
 	class ISmmPlugin;
diff --git a/core/ISmmPlugin.h b/core/ISmmPlugin.h
index c959556..ab750d6 100644
--- a/core/ISmmPlugin.h
+++ b/core/ISmmPlugin.h
@@ -34,7 +34,6 @@
  * The pure-virtual ISmmPlugin callbacks must be implemented for the load to load.
  */
 
-#include <interface.h>
 #include <sourcehook.h>
 #include <IPluginManager.h>
 #include <ISmmAPI.h>
@@ -268,7 +267,7 @@ namespace SourceMM
 		 * wrapper.  This can be used to provide interfaces to other plugins or
 		 * the GameDLL.
 		 *
-		 * If ret is passed, you should fill it with IFACE_OK or IFACE_FAILED.
+		 * If ret is passed, you should fill it with META_IFACE_OK or META_IFACE_FAILED.
 		 *
 		 * @param iface			Interface string.
 		 * @param ret			Optional pointer to store return code.
@@ -279,7 +278,7 @@ namespace SourceMM
 		{
 			if (ret)
 			{
-				*ret = IFACE_FAILED;
+				*ret = META_IFACE_FAILED;
 			}
 
 			return NULL; 
@@ -290,7 +289,7 @@ namespace SourceMM
 		 * Metamod:Source's wrapper. This can be used to provide interfaces to 
 		 * other plugins.
 		 *
-		 * If ret is passed, you should fill it with IFACE_OK or IFACE_FAILED.
+		 * If ret is passed, you should fill it with META_IFACE_OK or META_IFACE_FAILED.
 		 *
 		 * @param iface			Interface string.
 		 * @param ret			Optional pointer to store return code.
@@ -301,7 +300,7 @@ namespace SourceMM
 		{
 			if (ret)
 			{
-				*ret = IFACE_FAILED;
+				*ret = META_IFACE_FAILED;
 			}
 	
 			return NULL; 
@@ -312,7 +311,7 @@ namespace SourceMM
 		 * Metamod:Source's wrapper.  This can be used to provide interfaces to 
 		 * other plugins.
 		 *
-		 * If ret is passed, you should fill it with IFACE_OK or IFACE_FAILED.
+		 * If ret is passed, you should fill it with META_IFACE_OK or META_IFACE_FAILED.
 		 *
 		 * @param iface			Interface string.
 		 * @param ret			Optional pointer to store return code.
@@ -323,7 +322,7 @@ namespace SourceMM
 		{
 			if (ret)
 			{
-				*ret = IFACE_FAILED;
+				*ret = META_IFACE_FAILED;
 			}
 			
 			return NULL; 
@@ -334,7 +333,7 @@ namespace SourceMM
 		 * Metamod:Source's wrapper.  This can be used to provide interfaces to 
 		 * other plugins.
 		 *
-		 * If ret is passed, you should fill it with IFACE_OK or IFACE_FAILED.
+		 * If ret is passed, you should fill it with META_IFACE_OK or META_IFACE_FAILED.
 		 *
 		 * @param iface			Interface string.
 		 * @param ret			Optional pointer to store return code.
@@ -345,7 +344,7 @@ namespace SourceMM
 		{
 			if (ret)
 			{
-				*ret = IFACE_FAILED;
+				*ret = META_IFACE_FAILED;
 			}
 	
 			return NULL; 
@@ -355,7 +354,7 @@ namespace SourceMM
 		 * @brief Called when Metamod's own factory is invoked.  
 		 * This can be used to provide interfaces to other plugins.
 		 *
-		 * If ret is passed, you should fill it with IFACE_OK or IFACE_FAILED.
+		 * If ret is passed, you should fill it with META_IFACE_OK or META_IFACE_FAILED.
 		 *
 		 * @param iface			Interface string.
 		 * @param ret			Optional pointer to store return code.
@@ -366,7 +365,7 @@ namespace SourceMM
 		{
 			if (ret)
 			{
-				*ret = IFACE_FAILED;
+				*ret = META_IFACE_FAILED;
 			}
 	
 			return NULL;