diff --git a/renderdoc/driver/gl/gl_hooks_linux_shared.cpp b/renderdoc/driver/gl/gl_hooks_linux_shared.cpp
index 8816c6bc4..7ee9dc806 100644
--- a/renderdoc/driver/gl/gl_hooks_linux_shared.cpp
+++ b/renderdoc/driver/gl/gl_hooks_linux_shared.cpp
@@ -43,17 +43,19 @@ Threading::CriticalSection &GetGLLock()
   return glLock;
 }
 
-#define HookInit(function)                               \
-  if(!strcmp(func, STRINGIZE(function)))                 \
-  {                                                      \
-    GL.function = (CONCAT(function, _hooktype))realFunc; \
-    return (void *)&CONCAT(function, _renderdoc_hooked); \
+#define HookInit(function)                                 \
+  if(!strcmp(func, STRINGIZE(function)))                   \
+  {                                                        \
+    if(GL.function == NULL)                                \
+      GL.function = (CONCAT(function, _hooktype))realFunc; \
+    return (void *)&CONCAT(function, _renderdoc_hooked);   \
   }
 
 #define HookExtension(funcPtrType, function)             \
   if(!strcmp(func, STRINGIZE(function)))                 \
   {                                                      \
-    GL.function = (funcPtrType)realFunc;                 \
+    if(GL.function == NULL)                              \
+      GL.function = (funcPtrType)realFunc;               \
     return (void *)&CONCAT(function, _renderdoc_hooked); \
   }
 
diff --git a/renderdoc/driver/gl/gl_hooks_win32.cpp b/renderdoc/driver/gl/gl_hooks_win32.cpp
index ca855c3d4..86b136f25 100644
--- a/renderdoc/driver/gl/gl_hooks_win32.cpp
+++ b/renderdoc/driver/gl/gl_hooks_win32.cpp
@@ -44,14 +44,15 @@
 #define HookExtension(funcPtrType, function)         \
   if(!strcmp(func, STRINGIZE(function)))             \
   {                                                  \
-    glhooks.GL.function = (funcPtrType)realFunc;     \
+    if(glhooks.GL.function == NULL)                  \
+      glhooks.GL.function = (funcPtrType)realFunc;   \
     return (PROC)&glhooks.CONCAT(function, _hooked); \
   }
 
 #define HookExtensionAlias(funcPtrType, function, alias) \
   if(!strcmp(func, STRINGIZE(alias)))                    \
   {                                                      \
-    if(OpenGLHook::glhooks.GL.function == NULL)          \
+    if(glhooks.GL.function == NULL)                      \
       glhooks.GL.function = (funcPtrType)realFunc;       \
     return (PROC)&glhooks.CONCAT(function, _hooked);     \
   }