diff --git a/loopy/transform/precompute.py b/loopy/transform/precompute.py
index 7c20d7a01..31f0057c8 100644
--- a/loopy/transform/precompute.py
+++ b/loopy/transform/precompute.py
@@ -248,8 +248,7 @@ def map_kernel(self, kernel):
                     dep_insn = kernel.id_to_insn[dep]
                     if (frozenset(dep_insn.assignee_var_names())
                             & self.compute_read_variables):
-                        self.compute_insn_depends_on.update(
-                                insn.depends_on - excluded_insn_ids)
+                        self.compute_insn_depends_on.add(dep)
 
             new_insns.append(insn)