diff --git a/renderdoc/driver/gl/gl_hooks_linux.cpp b/renderdoc/driver/gl/gl_hooks_linux.cpp
index 6e520d8c9..2da389490 100644
--- a/renderdoc/driver/gl/gl_hooks_linux.cpp
+++ b/renderdoc/driver/gl/gl_hooks_linux.cpp
@@ -75,7 +75,8 @@ void *libGLdlsymHandle =
 #define HookExtensionAlias(funcPtrType, function, alias)          \
   if(!strcmp(func, STRINGIZE(alias)))                             \
   {                                                               \
-    OpenGLHook::glhooks.GL.function = (funcPtrType)realFunc;      \
+    if(OpenGLHook::glhooks.GL.function == NULL)                   \
+      OpenGLHook::glhooks.GL.function = (funcPtrType)realFunc;    \
     return (__GLXextFuncPtr)&CONCAT(function, _renderdoc_hooked); \
   }
 
diff --git a/renderdoc/driver/gl/gl_hooks_win32.cpp b/renderdoc/driver/gl/gl_hooks_win32.cpp
index b5d956dbe..6f57b68c2 100644
--- a/renderdoc/driver/gl/gl_hooks_win32.cpp
+++ b/renderdoc/driver/gl/gl_hooks_win32.cpp
@@ -56,7 +56,8 @@ void EmulateUnsupportedFunctions(GLHookSet *hooks);
 #define HookExtensionAlias(funcPtrType, function, alias) \
   if(!strcmp(func, STRINGIZE(alias)))                    \
   {                                                      \
-    glhooks.GL.function = (funcPtrType)realFunc;         \
+    if(OpenGLHook::glhooks.GL.function == NULL)          \
+      glhooks.GL.function = (funcPtrType)realFunc;       \
     return (PROC)&glhooks.CONCAT(function, _hooked);     \
   }