diff --git a/cmake/Modules/Packages/KIM.cmake b/cmake/Modules/Packages/KIM.cmake
index 2a2a1cde78..995d2d9490 100644
--- a/cmake/Modules/Packages/KIM.cmake
+++ b/cmake/Modules/Packages/KIM.cmake
@@ -19,7 +19,7 @@ if(CURL_FOUND)
     target_compile_definitions(lammps PRIVATE -DLMP_NO_SSL_CHECK)
   endif()
 endif()
-set(KIM_EXTRA_UNITTESTS OFF CACHE STRING "Set extra unit tests verbose mode on/off. If on, extra tests are included.")
+option(KIM_EXTRA_UNITTESTS "Enable extra unit tests for the KIM package." OFF)
 mark_as_advanced(KIM_EXTRA_UNITTESTS)
 find_package(PkgConfig QUIET)
 set(DOWNLOAD_KIM_DEFAULT ON)
diff --git a/unittest/commands/test_kim_commands.cpp b/unittest/commands/test_kim_commands.cpp
index 988b0db69a..2e6e758c76 100644
--- a/unittest/commands/test_kim_commands.cpp
+++ b/unittest/commands/test_kim_commands.cpp
@@ -92,14 +92,14 @@ TEST_F(KimCommandsTest, kim_interactions)
 {
     if (!LAMMPS::is_installed_pkg("KIM")) GTEST_SKIP();
 
-    TEST_FAILURE(".*ERROR: Illegal 'kim interactions' command.*", command("kim interactions"););
+    TEST_FAILURE(".*ERROR: Illegal kim interactions command: missing argument.*",
+                 command("kim interactions"););
 
     BEGIN_HIDE_OUTPUT();
     command("kim init LennardJones_Ar real");
     END_HIDE_OUTPUT();
 
-    TEST_FAILURE(".*ERROR: Must use 'kim interactions' command "
-                 "after simulation box is defined.*",
+    TEST_FAILURE(".*ERROR: Use of 'kim interactions' before simulation box is defined.*",
                  command("kim interactions Ar"););
 
     BEGIN_HIDE_OUTPUT();
@@ -410,11 +410,11 @@ TEST_F(KimCommandsTest, kim_property)
                      "3 >= 3.6 support.*",
                      command("kim property"););
     } else {
-        TEST_FAILURE(".*ERROR: Invalid 'kim property' command.*", command("kim property"););
-        TEST_FAILURE(".*ERROR: Invalid 'kim property' command.*", command("kim property create"););
-        TEST_FAILURE(".*ERROR: Incorrect arguments in 'kim property' command."
-                     "\n'kim property create/destroy/modify/remove/dump' "
-                     "is mandatory.*",
+        TEST_FAILURE(".*ERROR: Illegal kim property command: missing argument.*",
+                     command("kim property"););
+        TEST_FAILURE(".*ERROR: Illegal kim property command: missing argument.*",
+                     command("kim property create"););
+        TEST_FAILURE(".*ERROR: Incorrect first argument unknown to 'kim property' command.*",
                      command("kim property unknown 1 atomic-mass"););
     }
 #if defined(KIM_EXTRA_UNITTESTS)