diff --git a/src/mapi/glapi/gen/ARB_debug_output.xml b/src/mapi/glapi/gen/ARB_debug_output.xml
index 11f268dc640..f2877a4f7d3 100644
--- a/src/mapi/glapi/gen/ARB_debug_output.xml
+++ b/src/mapi/glapi/gen/ARB_debug_output.xml
@@ -72,7 +72,7 @@
 
     <function name="DebugMessageCallbackARB" offset="assign">
         <param name="callback" type="GLDEBUGPROCARB"/>
-        <param name="userParam" type="const GLvoid *"/>
+        <param name="userParam" type="GLvoid *"/>
     </function>
 
     <function name="GetDebugMessageLogARB" offset="assign">
diff --git a/src/mesa/main/errors.c b/src/mesa/main/errors.c
index cc652bac8f8..465420766f7 100644
--- a/src/mesa/main/errors.c
+++ b/src/mesa/main/errors.c
@@ -659,11 +659,11 @@ _mesa_DebugMessageControlARB(GLenum gl_source, GLenum gl_type,
 }
 
 void GLAPIENTRY
-_mesa_DebugMessageCallbackARB(GLDEBUGPROCARB callback, const GLvoid *userParam)
+_mesa_DebugMessageCallbackARB(GLDEBUGPROCARB callback, GLvoid *userParam)
 {
    GET_CURRENT_CONTEXT(ctx);
    ctx->Debug.Callback = callback;
-   ctx->Debug.CallbackData = (void *) userParam;
+   ctx->Debug.CallbackData = userParam;
 }
 
 void
diff --git a/src/mesa/main/errors.h b/src/mesa/main/errors.h
index 7e7503aa984..4b376fb6075 100644
--- a/src/mesa/main/errors.h
+++ b/src/mesa/main/errors.h
@@ -101,7 +101,7 @@ _mesa_DebugMessageControlARB(GLenum source, GLenum type, GLenum severity,
                              GLboolean enabled);
 void GLAPIENTRY
 _mesa_DebugMessageCallbackARB(GLDEBUGPROCARB callback,
-                              const GLvoid *userParam);
+                              GLvoid *userParam);
 
 #ifdef __cplusplus
 }