diff --git a/ice40/arch.cc b/ice40/arch.cc
index 6679217a..5c632faa 100644
--- a/ice40/arch.cc
+++ b/ice40/arch.cc
@@ -806,53 +806,4 @@ void Arch::assignCellInfo(CellInfo *cell)
     }
 }
 
-std::unique_ptr<CellInfo> Arch::spliceLUT(CellInfo *ci, IdString portId, bool onlyNonLUTs)
-{
-     auto port = ci->ports[portId];
-
-     NPNR_ASSERT(port.net != nullptr);
-
-
-     // Create pass-through LUT.
-     std::unique_ptr<CellInfo> pt =
-         create_ice_cell(getCtx(), id("ICESTORM_LC"), ci->name.str(this) + "$nextpnr_ice40_pack_pll_lc");
-     pt->params[id("LUT_INIT")] = "255";  // output is always I3
-
-     // Create LUT output net.
-     std::unique_ptr<NetInfo> out_net = std::unique_ptr<NetInfo>(new NetInfo);
-     out_net->name = id(ci->name.str(this) + "$nextnr_ice40_pack_pll_net");
-     out_net->driver.cell = pt.get();
-     out_net->driver.port = id("O");
-     pt->ports.at(id("O")).net = out_net.get();
-
-     // New users of the original cell's port
-     std::vector<PortRef> new_users;
-     for (const auto &user : port.net->users) {
-         if (onlyNonLUTs && user.cell->type == id("ICESTORM_LC")) {
-             new_users.push_back(user);
-             continue;
-         }
-         // Rewrite pointer into net in user.
-         user.cell->ports[user.port].net = out_net.get();
-         // Add user to net.
-         PortRef pr;
-         pr.cell = user.cell;
-         pr.port = user.port;
-         out_net->users.push_back(pr);
-     }
-
-     // Add LUT to new users.
-     PortRef pr;
-     pr.cell = pt.get();
-     pr.port = id("I3");
-     new_users.push_back(pr);
-     pt->ports.at(id("I3")).net = port.net;
-
-     // Replace users of the original net.
-     port.net->users = new_users;
-
-     nets[out_net->name] = std::move(out_net);
-     return pt;
-}
-
 NEXTPNR_NAMESPACE_END
diff --git a/ice40/arch.h b/ice40/arch.h
index 15422aa7..d4d71cfc 100644
--- a/ice40/arch.h
+++ b/ice40/arch.h
@@ -746,11 +746,6 @@ struct Arch : BaseCtx
     IdString id_cen, id_clk, id_sr;
     IdString id_i0, id_i1, id_i2, id_i3;
     IdString id_dff_en, id_neg_clk;
-
-
-    // -------------------------------------------------
-    // Insert a LUT/LC in between a given output port of a cell and all its' users.
-    std::unique_ptr<CellInfo> spliceLUT(CellInfo *ci, IdString portId, bool onlyNonLUTs);
 };
 
 NEXTPNR_NAMESPACE_END
diff --git a/ice40/pack.cc b/ice40/pack.cc
index dc0db578..14abc1d0 100644
--- a/ice40/pack.cc
+++ b/ice40/pack.cc
@@ -537,6 +537,57 @@ static void promote_globals(Context *ctx)
     }
 }
 
+// spliceLUT adds a pass-through LUT LC between the given cell's output port
+// and either all users or only non_LUT users.
+static std::unique_ptr<CellInfo> spliceLUT(Context *ctx, CellInfo *ci, IdString portId, bool onlyNonLUTs)
+{
+     auto port = ci->ports[portId];
+
+     NPNR_ASSERT(port.net != nullptr);
+
+
+     // Create pass-through LUT.
+     std::unique_ptr<CellInfo> pt =
+         create_ice_cell(ctx, ctx->id("ICESTORM_LC"), ci->name.str(ctx) + "$nextpnr_ice40_pack_pll_lc");
+     pt->params[ctx->id("LUT_INIT")] = "255";  // output is always I3
+
+     // Create LUT output net.
+     std::unique_ptr<NetInfo> out_net = std::unique_ptr<NetInfo>(new NetInfo);
+     out_net->name = ctx->id(ci->name.str(ctx) + "$nextnr_ice40_pack_pll_net");
+     out_net->driver.cell = pt.get();
+     out_net->driver.port = ctx->id("O");
+     pt->ports.at(ctx->id("O")).net = out_net.get();
+
+     // New users of the original cell's port
+     std::vector<PortRef> new_users;
+     for (const auto &user : port.net->users) {
+         if (onlyNonLUTs && user.cell->type == ctx->id("ICESTORM_LC")) {
+             new_users.push_back(user);
+             continue;
+         }
+         // Rewrite pointer into net in user.
+         user.cell->ports[user.port].net = out_net.get();
+         // Add user to net.
+         PortRef pr;
+         pr.cell = user.cell;
+         pr.port = user.port;
+         out_net->users.push_back(pr);
+     }
+
+     // Add LUT to new users.
+     PortRef pr;
+     pr.cell = pt.get();
+     pr.port = ctx->id("I3");
+     new_users.push_back(pr);
+     pt->ports.at(ctx->id("I3")).net = port.net;
+
+     // Replace users of the original net.
+     port.net->users = new_users;
+
+     ctx->nets[out_net->name] = std::move(out_net);
+     return pt;
+}
+
 // Pack special functions
 static void pack_special(Context *ctx)
 {
@@ -674,12 +725,12 @@ static void pack_special(Context *ctx)
                 } else if (found_lut && !all_luts && lut_count < 8) {
                     // Strategy: create a pass-through LUT, move all non-LUT users behind it.
                     log_info("    LUT strategy for %s: move non-LUT users to new LUT\n", port.name.c_str(ctx));
-                    auto pt = ctx->spliceLUT(packed.get(), port.name, true);
+                    auto pt = spliceLUT(ctx, packed.get(), port.name, true);
                     new_cells.push_back(std::move(pt));
                 } else {
                     // Strategy: create a pass-through LUT, move every user behind it.
                     log_info("    LUT strategy for %s: move all users to new LUT\n", port.name.c_str(ctx));
-                    auto pt = ctx->spliceLUT(packed.get(), port.name, false);
+                    auto pt = spliceLUT(ctx, packed.get(), port.name, false);
                     new_cells.push_back(std::move(pt));
                 }