diff --git a/unittest/commands/CMakeLists.txt b/unittest/commands/CMakeLists.txt
index f6a73b56b3..1a9984a20e 100644
--- a/unittest/commands/CMakeLists.txt
+++ b/unittest/commands/CMakeLists.txt
@@ -11,8 +11,17 @@ endif()
 
 target_link_libraries(test_simple_commands PRIVATE lammps GTest::GMock)
 add_test(NAME SimpleCommands COMMAND test_simple_commands)
-set_tests_properties(SimpleCommands PROPERTIES
-          ENVIRONMENT "LAMMPS_PLUGIN_BIN_DIR=${CMAKE_BINARY_DIR}")
+if(CMAKE_VERSION VERSION_LESS 3.20)
+  set_tests_properties(SimpleCommands PROPERTIES
+                       ENVIRONMENT "LAMMPS_PLUGIN_DIR=${CMAKE_BINARY_DIR}")
+else()
+  cmake_path(SET LAMMPS_PLUGIN_BIN_DIR NORMALIZE ${CMAKE_BINARY_DIR})
+  if(CMAKE_CONFIG_TYPE)
+    cmake_path(APPEND LAMMPS_PLUGIN_BIN_DIR ${CMAKE_CONFIG_TYPE})
+  endif()
+  set_tests_properties(SimpleCommands PROPERTIES
+                       ENVIRONMENT "LAMMPS_PLUGIN_DIR=${LAMMPS_PLUGIN_BIN_DIR}")
+endif()
 
 add_executable(test_lattice_region test_lattice_region.cpp)
 target_link_libraries(test_lattice_region PRIVATE lammps GTest::GMock)
diff --git a/unittest/commands/test_simple_commands.cpp b/unittest/commands/test_simple_commands.cpp
index 7e52d24eca..9460a723ee 100644
--- a/unittest/commands/test_simple_commands.cpp
+++ b/unittest/commands/test_simple_commands.cpp
@@ -411,12 +411,9 @@ TEST_F(SimpleCommandsTest, Units)
 #if defined(LMP_PLUGIN)
 TEST_F(SimpleCommandsTest, Plugin)
 {
-    const char *bindir = getenv("LAMMPS_PLUGIN_BIN_DIR");
-    const char *config = getenv("CMAKE_CONFIG_TYPE");
-    if (!bindir) GTEST_SKIP() << "LAMMPS_PLUGIN_BIN_DIR not set";
-    std::string loadfmt = platform::path_join("plugin load ", bindir);
-    if (config) loadfmt = platform::path_join(loadfmt, config);
-    loadfmt = platform::path_join(loadfmt, "{}plugin.so");
+    const char *bindir = getenv("LAMMPS_PLUGIN_DIR");
+    if (!bindir) GTEST_SKIP() << "LAMMPS_PLUGIN_DIR not set";
+    std::string loadfmt = "plugin load {}plugin.so";
     ::testing::internal::CaptureStdout();
     lmp->input->one(fmt::format(loadfmt, "hello"));
     auto text = ::testing::internal::GetCapturedStdout();
@@ -438,8 +435,7 @@ TEST_F(SimpleCommandsTest, Plugin)
     lmp->input->one("plugin list");
     text = ::testing::internal::GetCapturedStdout();
     if (verbose) std::cout << text;
-    ASSERT_THAT(text, ContainsRegex(".*1: command style plugin hello"
-                                    ".*2: fix style plugin nve2.*"));
+    ASSERT_THAT(text, ContainsRegex(".*1: command style plugin hello\n.*2: fix style plugin nve2.*"));
 
     ::testing::internal::CaptureStdout();
     lmp->input->one(fmt::format(loadfmt, "hello"));