diff --git a/common/kernel/arch_api.h b/common/kernel/arch_api.h
index 14a30652..49be489b 100644
--- a/common/kernel/arch_api.h
+++ b/common/kernel/arch_api.h
@@ -93,7 +93,7 @@ template <typename R> struct ArchAPI : BaseCtx
     virtual void bindPip(PipId pip, NetInfo *net, PlaceStrength strength) = 0;
     virtual void unbindPip(PipId pip) = 0;
     virtual bool checkPipAvail(PipId pip) const = 0;
-    virtual bool checkPipAvailForNet(PipId pip, NetInfo *net) const = 0;
+    virtual bool checkPipAvailForNet(PipId pip, const NetInfo *net) const = 0;
     virtual NetInfo *getBoundPipNet(PipId pip) const = 0;
     virtual WireId getConflictingPipWire(PipId pip) const = 0;
     virtual NetInfo *getConflictingPipNet(PipId pip) const = 0;
diff --git a/common/kernel/base_arch.h b/common/kernel/base_arch.h
index 3055619d..55fcf280 100644
--- a/common/kernel/base_arch.h
+++ b/common/kernel/base_arch.h
@@ -274,7 +274,7 @@ template <typename R> struct BaseArch : ArchAPI<R>
         p2n_entry = nullptr;
     }
     virtual bool checkPipAvail(PipId pip) const override { return getBoundPipNet(pip) == nullptr; }
-    virtual bool checkPipAvailForNet(PipId pip, NetInfo *net) const override
+    virtual bool checkPipAvailForNet(PipId pip, const NetInfo *net) const override
     {
         NetInfo *bound_net = getBoundPipNet(pip);
         return bound_net == nullptr || bound_net == net;
diff --git a/docs/archapi.md b/docs/archapi.md
index 3fc30cdb..efd833d2 100644
--- a/docs/archapi.md
+++ b/docs/archapi.md
@@ -402,7 +402,7 @@ pip to a net.
 
 *BaseArch default: returns `getBoundPipNet(pip) == nullptr`*
 
-### bool checkPipAvailForNet(PipId pip, NetInfo *net) const
+### bool checkPipAvailForNet(PipId pip, const NetInfo *net) const
 
 Returns true if the given pip is available to be bound to a net, or if the
 pip is already bound to that net.
diff --git a/ecp5/arch.h b/ecp5/arch.h
index 12f043b7..86504520 100644
--- a/ecp5/arch.h
+++ b/ecp5/arch.h
@@ -847,7 +847,7 @@ struct Arch : BaseArch<ArchRanges>
         return false;
     }
     bool checkPipAvail(PipId pip) const override { return (getBoundPipNet(pip) == nullptr) && !is_pip_blocked(pip); }
-    bool checkPipAvailForNet(PipId pip, NetInfo *net) const override
+    bool checkPipAvailForNet(PipId pip, const NetInfo *net) const override
     {
         NetInfo *bound_net = getBoundPipNet(pip);
         return (bound_net == nullptr || bound_net == net) && !is_pip_blocked(pip);
diff --git a/fpga_interchange/arch.cc b/fpga_interchange/arch.cc
index 3ce9f79e..4fc5d48d 100644
--- a/fpga_interchange/arch.cc
+++ b/fpga_interchange/arch.cc
@@ -1743,7 +1743,7 @@ void Arch::bindWire(WireId wire, NetInfo *net, PlaceStrength strength)
     refreshUiWire(wire);
 }
 
-bool Arch::checkPipAvailForNet(PipId pip, NetInfo *net) const
+bool Arch::checkPipAvailForNet(PipId pip, const NetInfo *net) const
 {
     NPNR_ASSERT(pip != PipId());
     auto pip_iter = pip_to_net.find(pip);
diff --git a/fpga_interchange/arch.h b/fpga_interchange/arch.h
index aeb5578f..04f583d4 100644
--- a/fpga_interchange/arch.h
+++ b/fpga_interchange/arch.h
@@ -596,7 +596,7 @@ struct Arch : ArchAPI<ArchRanges>
     void unbindPip(PipId pip) final;
 
     bool checkPipAvail(PipId pip) const final;
-    bool checkPipAvailForNet(PipId pip, NetInfo *net) const final;
+    bool checkPipAvailForNet(PipId pip, const NetInfo *net) const final;
 
     NetInfo *getBoundPipNet(PipId pip) const final
     {
diff --git a/generic/arch.cc b/generic/arch.cc
index 9992e1cd..a1d98200 100644
--- a/generic/arch.cc
+++ b/generic/arch.cc
@@ -468,7 +468,7 @@ bool Arch::checkPipAvail(PipId pip) const
     return (!uarch || uarch->checkPipAvail(pip)) && (pip_info(pip).bound_net == nullptr);
 }
 
-bool Arch::checkPipAvailForNet(PipId pip, NetInfo *net) const
+bool Arch::checkPipAvailForNet(PipId pip, const NetInfo *net) const
 {
     if (uarch && !uarch->checkPipAvailForNet(pip, net))
         return false;
diff --git a/generic/arch.h b/generic/arch.h
index 688392da..6b34c289 100644
--- a/generic/arch.h
+++ b/generic/arch.h
@@ -294,7 +294,7 @@ struct Arch : BaseArch<ArchRanges>
     void bindPip(PipId pip, NetInfo *net, PlaceStrength strength) override;
     void unbindPip(PipId pip) override;
     bool checkPipAvail(PipId pip) const override;
-    bool checkPipAvailForNet(PipId pip, NetInfo *net) const override;
+    bool checkPipAvailForNet(PipId pip, const NetInfo *net) const override;
     NetInfo *getBoundPipNet(PipId pip) const override;
     WireId getConflictingPipWire(PipId pip) const override;
     NetInfo *getConflictingPipNet(PipId pip) const override;
diff --git a/generic/viaduct_api.h b/generic/viaduct_api.h
index bc9b4311..6f8adb3e 100644
--- a/generic/viaduct_api.h
+++ b/generic/viaduct_api.h
@@ -77,7 +77,7 @@ struct ViaductAPI
     // it's bound (which the base arch will deal with)
     virtual bool checkWireAvail(WireId wire) const { return true; }
     virtual bool checkPipAvail(PipId pip) const { return true; }
-    virtual bool checkPipAvailForNet(PipId pip, NetInfo *net) const { return checkPipAvail(pip); };
+    virtual bool checkPipAvailForNet(PipId pip, const NetInfo *net) const { return checkPipAvail(pip); };
 
     // --- Route lookahead ---
     virtual delay_t estimateDelay(WireId src, WireId dst) const;
diff --git a/ice40/arch.h b/ice40/arch.h
index 5ed2347d..498a8b71 100644
--- a/ice40/arch.h
+++ b/ice40/arch.h
@@ -680,7 +680,7 @@ struct Arch : BaseArch<ArchRanges>
         return switches_locked[pi.switch_index] == WireId();
     }
 
-    bool checkPipAvailForNet(PipId pip, NetInfo *net) const override
+    bool checkPipAvailForNet(PipId pip, const NetInfo *net) const override
     {
         if (ice40_pip_hard_unavail(pip))
             return false;
diff --git a/mistral/arch.h b/mistral/arch.h
index 8fcea291..5ceda53c 100644
--- a/mistral/arch.h
+++ b/mistral/arch.h
@@ -408,7 +408,7 @@ struct Arch : BaseArch<ArchRanges>
         return BaseArch::checkPipAvail(pip);
     }
 
-    bool checkPipAvailForNet(PipId pip, NetInfo *net) const override
+    bool checkPipAvailForNet(PipId pip, const NetInfo *net) const override
     {
         if (is_pip_blocked(pip))
             return false;
diff --git a/nexus/arch.h b/nexus/arch.h
index df4f976a..41c54cd8 100644
--- a/nexus/arch.h
+++ b/nexus/arch.h
@@ -1018,7 +1018,7 @@ struct Arch : BaseArch<ArchRanges>
         return getBoundPipNet(pip) == nullptr;
     }
 
-    bool checkPipAvailForNet(PipId pip, NetInfo *net) const override
+    bool checkPipAvailForNet(PipId pip, const NetInfo *net) const override
     {
         if (disabled_pips.count(pip))
             return false;