diff --git a/cmake/Modules/YAML.cmake b/cmake/Modules/YAML.cmake
index c50773568c..77ee804111 100644
--- a/cmake/Modules/YAML.cmake
+++ b/cmake/Modules/YAML.cmake
@@ -6,15 +6,27 @@ set(YAML_MD5 "bb15429d8fb787e7d3f1c83ae129a999" CACHE STRING "MD5 checksum of li
 mark_as_advanced(YAML_URL)
 mark_as_advanced(YAML_MD5)
 
+# support cross-compilation to windows
+if(CMAKE_CROSSCOMPILING AND (CMAKE_SYSTEM_NAME STREQUAL "Windows"))
+  if(CMAKE_SYSTEM_PROCESSOR STREQUAL "x86")
+    set(YAML_CROSS_HOST --host=i686-mingw64)
+  elseif(CMAKE_SYSTEM_PROCESSOR STREQUAL "x86_64")
+    set(YAML_CROSS_HOST --host=x86_64-mingw64)
+  else()
+    message(FATAL_ERROR "Unsupported cross-compilation "
+      " for ${CMAKE_SYSTEM_NAME}/${CMAKE_SYSTEM_PROCESSOR}"
+      " on ${CMAKE_HOST_SYSTEM}/${CMAKE_HOST_SYSTEM_PROCESSOR}")
+  endif()
+endif()
+
 ExternalProject_Add(libyaml
                     URL               ${YAML_URL}
                     URL_MD5           ${YAML_MD5}
                     SOURCE_DIR        "${CMAKE_BINARY_DIR}/yaml-src"
                     BINARY_DIR        "${CMAKE_BINARY_DIR}/yaml-build"
                     CONFIGURE_COMMAND <SOURCE_DIR>/configure ${CONFIGURE_REQUEST_PIC}
-                                      CXX=${CMAKE_CXX_COMPILER}
-                                      CC=${CMAKE_C_COMPILER}
-                                      --prefix=<INSTALL_DIR> --disable-shared
+                                      CXX=${CMAKE_CXX_COMPILER} CC=${CMAKE_C_COMPILER}
+                                      --prefix=<INSTALL_DIR> --disable-shared ${YAML_CROSS_HOST}
                     BUILD_BYPRODUCTS  <INSTALL_DIR>/lib/libyaml${CMAKE_STATIC_LIBRARY_SUFFIX}
                     TEST_COMMAND      "")
 
diff --git a/unittest/cplusplus/test_lammps_class.cpp b/unittest/cplusplus/test_lammps_class.cpp
index 04ad403db6..5288cfc2b6 100644
--- a/unittest/cplusplus/test_lammps_class.cpp
+++ b/unittest/cplusplus/test_lammps_class.cpp
@@ -362,7 +362,11 @@ TEST(LAMMPS_init, NoOpenMP)
     FILE *fp = fopen("in.lammps_class_noomp", "w");
     fputs("\n", fp);
     fclose(fp);
+#if defined(__WIN32)
+    _putenv("OMP_NUM_THREADS");
+#else
     unsetenv("OMP_NUM_THREADS");
+#endif
 
     const char *args[] = {"LAMMPS_init", "-in", "in.lammps_class_noomp", "-log", "none", "-nocite"};
     char **argv        = (char **)args;
diff --git a/unittest/force-styles/CMakeLists.txt b/unittest/force-styles/CMakeLists.txt
index 2c0977397a..86b0f4fdaf 100644
--- a/unittest/force-styles/CMakeLists.txt
+++ b/unittest/force-styles/CMakeLists.txt
@@ -26,7 +26,7 @@ set(TEST_INPUT_FOLDER ${CMAKE_CURRENT_SOURCE_DIR}/tests)
 add_library(style_tests STATIC yaml_writer.cpp error_stats.cpp test_config_reader.cpp test_main.cpp)
 target_compile_definitions(style_tests PRIVATE -DTEST_INPUT_FOLDER=${TEST_INPUT_FOLDER})
 target_include_directories(style_tests PRIVATE ${LAMMPS_SOURCE_DIR})
-target_link_libraries(style_tests PUBLIC GTest::GTest GTest::GMock Yaml::Yaml)
+target_link_libraries(style_tests PUBLIC GTest::GTest GTest::GMock Yaml::Yaml lammps)
 if(BUILD_MPI)
   target_link_libraries(style_tests PUBLIC MPI::MPI_CXX)
 else()
diff --git a/unittest/fortran/CMakeLists.txt b/unittest/fortran/CMakeLists.txt
index fe63802e8b..9bd6c8f419 100644
--- a/unittest/fortran/CMakeLists.txt
+++ b/unittest/fortran/CMakeLists.txt
@@ -7,6 +7,7 @@ endif()
 include(CheckLanguage)
 check_language(Fortran)
 if(CMAKE_Fortran_COMPILER)
+  enable_language(C)
   enable_language(Fortran)
   get_filename_component(LAMMPS_FORTRAN_MODULE ${LAMMPS_SOURCE_DIR}/../fortran/lammps.f90 ABSOLUTE)
   if(BUILD_MPI)