diff --git a/src/gallium/winsys/radeon/drm/radeon_drm_cs.c b/src/gallium/winsys/radeon/drm/radeon_drm_cs.c
index fd52a40..2ca0950 100644
--- a/src/gallium/winsys/radeon/drm/radeon_drm_cs.c
+++ b/src/gallium/winsys/radeon/drm/radeon_drm_cs.c
@@ -593,18 +593,20 @@
             fence = radeon_cs_create_fence(rcs);
         }
 
-        if (pfence)
-            radeon_fence_reference(pfence, fence);
+        if (fence) {
+            if (pfence)
+                radeon_fence_reference(pfence, fence);
 
-        pipe_mutex_lock(cs->ws->bo_fence_lock);
-        for (unsigned i = 0; i < cs->csc->num_slab_buffers; ++i) {
-            struct radeon_bo *bo = cs->csc->slab_buffers[i].bo;
-            p_atomic_inc(&bo->num_active_ioctls);
-            radeon_bo_slab_fence(bo, (struct radeon_bo *)fence);
+            pipe_mutex_lock(cs->ws->bo_fence_lock);
+            for (unsigned i = 0; i < cs->csc->num_slab_buffers; ++i) {
+                struct radeon_bo *bo = cs->csc->slab_buffers[i].bo;
+                p_atomic_inc(&bo->num_active_ioctls);
+                radeon_bo_slab_fence(bo, (struct radeon_bo *)fence);
+            }
+            pipe_mutex_unlock(cs->ws->bo_fence_lock);
+
+            radeon_fence_reference(&fence, NULL);
         }
-        pipe_mutex_unlock(cs->ws->bo_fence_lock);
-
-        radeon_fence_reference(&fence, NULL);
     } else {
         radeon_fence_reference(&cs->next_fence, NULL);
     }