diff --git a/difftest/spike_interfaces/CMakeLists.txt b/difftest/spike_interfaces/CMakeLists.txt
index 6da21334c..fe5272891 100644
--- a/difftest/spike_interfaces/CMakeLists.txt
+++ b/difftest/spike_interfaces/CMakeLists.txt
@@ -4,7 +4,7 @@ set(CMAKE_CXX_STANDARD 17)
 
 find_package(libspike REQUIRED)
 
-add_library(${CMAKE_PROJECT_NAME} SHARED spike_interfaces.cc)
+add_library(${CMAKE_PROJECT_NAME} STATIC spike_interfaces.cc)
 
 target_link_libraries(${CMAKE_PROJECT_NAME} PUBLIC libspike)
 
diff --git a/nix/overlay.nix b/nix/overlay.nix
index d0ca888b5..4dae99039 100644
--- a/nix/overlay.nix
+++ b/nix/overlay.nix
@@ -18,7 +18,6 @@ rec {
   espresso = final.callPackage ./pkgs/espresso.nix { };
   dramsim3 = final.callPackage ./pkgs/dramsim3.nix { };
   libspike = final.callPackage ./pkgs/libspike.nix { };
-  libspike_interfaces = final.callPackage ../difftest/libspike_interfaces { };
   buddy-mlir = final.callPackage ./pkgs/buddy-mlir.nix { };
   fetchMillDeps = final.callPackage ./pkgs/mill-builder.nix { };
   circt-full = final.callPackage ./pkgs/circt-full.nix { };
diff --git a/nix/pkgs/libspike.nix b/nix/pkgs/libspike.nix
index dc3a28fdc..1ecb1c317 100644
--- a/nix/pkgs/libspike.nix
+++ b/nix/pkgs/libspike.nix
@@ -7,7 +7,7 @@ stdenv.mkDerivation {
   env.cmakeConfig = ''
     add_library(libspike STATIC IMPORTED GLOBAL)
     set_target_properties(libspike PROPERTIES
-      IMPORTED_LOCATION "${placeholder "out"}/lib/libriscv.so")
+      IMPORTED_LOCATION "${placeholder "out"}/lib/libriscv.a")
     target_include_directories(libspike AFTER INTERFACE
       "${placeholder "out"}/include"
       "${placeholder "out"}/include/riscv"
@@ -37,6 +37,7 @@ stdenv.mkDerivation {
     cp softfloat/*.h $out/include/softfloat
     cp config.h $out/include
     cp *.so $out/lib
+    cp *.a $out/lib
     echo "$cmakeConfig" > $out/lib/cmake/libspike/libspike-config.cmake
     runHook postInstall
   '';