diff --git a/gasket_core.c b/gasket_core.c
index 7b912f1..43c63da 100644
--- a/gasket_core.c
+++ b/gasket_core.c
@@ -1637,7 +1637,7 @@ static int gasket_mmap(struct file *filp, struct vm_area_struct *vma)
 			"0x%lx",
 			raw_offset);
 		trace_gasket_mmap_exit(bar_index);
-		return bar_index;
+		return -EINVAL;
 	}
 
 	vma->vm_private_data = gasket_dev;