diff --git a/shared-core/radeon_irq.c b/shared-core/radeon_irq.c
index 60654b2..9ede679 100644
--- a/shared-core/radeon_irq.c
+++ b/shared-core/radeon_irq.c
@@ -295,6 +295,9 @@ u32 radeon_get_vblank_counter(struct drm_device *dev, int crtc)
 		return -EINVAL;
 	}
 
+	if (!dev_priv->mmio)
+		return -EINVAL;
+
 	if ((dev_priv->flags & RADEON_FAMILY_MASK) >= CHIP_RS690) {
 		if (crtc == 0)
 			return RADEON_READ(R500_D1CRTC_FRAME_COUNT);