diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4c222d71..0cf55eb8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,6 +5,13 @@ project(nextpnr)
 option(BUILD_GUI "Build GUI" ON)
 option(BUILD_PYTHON "Build Python Integration" ON)
 option(BUILD_TESTS "Build GUI" OFF)
+option(STATIC_BUILD "Create static build" OFF)
+
+set(link_param "")
+if (STATIC_BUILD)
+    set(Boost_USE_STATIC_LIBS   ON)
+    set(link_param "-static")
+endif()
 
 # List of families to build
 set(FAMILIES generic ice40 ecp5)
@@ -211,7 +218,7 @@ foreach (family ${ARCH})
         # Include family-specific source files to all family targets and set defines appropriately
         target_include_directories(${target} PRIVATE ${family}/ ${CMAKE_CURRENT_BINARY_DIR}/generated/)
         target_compile_definitions(${target} PRIVATE NEXTPNR_NAMESPACE=nextpnr_${family} ARCH_${ufamily} ARCHNAME=${family})
-        target_link_libraries(${target} LINK_PUBLIC ${Boost_LIBRARIES})
+        target_link_libraries(${target} LINK_PUBLIC ${Boost_LIBRARIES} ${link_param})
         if (NOT MSVC)
             target_link_libraries(${target} LINK_PUBLIC pthread)
         endif()
diff --git a/README.md b/README.md
index e9f197cd..a47a06a7 100644
--- a/README.md
+++ b/README.md
@@ -127,6 +127,13 @@ cmake -DARCH=ice40 -DCMAKE_BUILD_TYPE=Debug -DBUILD_PYTHON=OFF -DBUILD_GUI=OFF -
 make -j$(nproc)
 ```
 
+To make static build relase for iCE40 architecture use the following:
+
+```
+cmake -DARCH=ice40 -DBUILD_PYTHON=OFF -DBUILD_GUI=OFF -DSTATIC_BUILD=ON .
+make -j$(nproc)
+```
+
 Notes for developers
 --------------------
 
diff --git a/ecp5/arch.cc b/ecp5/arch.cc
index 4358fdaf..fec1011c 100644
--- a/ecp5/arch.cc
+++ b/ecp5/arch.cc
@@ -367,7 +367,7 @@ BelId Arch::getBelByLocation(Loc loc) const
 
 delay_t Arch::estimateDelay(WireId src, WireId dst) const
 {
-    return 200 * (abs(src.location.x - dst.location.x) + abs(src.location.y - dst.location.y));
+    return 50 * (abs(src.location.x - dst.location.x) + abs(src.location.y - dst.location.y));
 }
 
 delay_t Arch::predictDelay(const NetInfo *net_info, const PortRef &sink) const
@@ -376,7 +376,7 @@ delay_t Arch::predictDelay(const NetInfo *net_info, const PortRef &sink) const
     auto driver_loc = getBelLocation(driver.cell->bel);
     auto sink_loc = getBelLocation(sink.cell->bel);
 
-    return 200 * (abs(driver_loc.x - sink_loc.x) + abs(driver_loc.y - sink_loc.y));
+    return 50 * (abs(driver_loc.x - sink_loc.x) + abs(driver_loc.y - sink_loc.y));
 }
 
 bool Arch::getBudgetOverride(const NetInfo *net_info, const PortRef &sink, delay_t &budget) const { return false; }
diff --git a/ice40/bitstream.cc b/ice40/bitstream.cc
index ee276e49..4ea91011 100644
--- a/ice40/bitstream.cc
+++ b/ice40/bitstream.cc
@@ -870,10 +870,12 @@ bool read_asc(Context *ctx, std::istream &in)
             }
             if (isUsed) {
                 NetInfo *net = ctx->wire_to_net[pi.dst];
-                WireId wire;
-                wire.index = pi.dst;
-                ctx->unbindWire(wire);
-                ctx->bindPip(pip, net, STRENGTH_WEAK);
+                if (net!=nullptr) {
+                    WireId wire;
+                    wire.index = pi.dst;
+                    ctx->unbindWire(wire);
+                    ctx->bindPip(pip, net, STRENGTH_WEAK);
+                }
             }
         }
         for (auto bel : ctx->getBels()) {