diff --git a/unittests/test_18.c b/unittests/test_18.c
new file mode 100644
index 0000000..7df29c5
--- /dev/null
+++ b/unittests/test_18.c
@@ -0,0 +1,8 @@
+#include "tests.h"
+
+void test_18()
+{
+    printf("TEST 18 STARTET\n");
+    assert(!compareStrings("PC", "PC"));
+    printf("TEST 18 ERFOLGREICH\n");
+}
\ No newline at end of file
diff --git a/unittests/test_main.c b/unittests/test_main.c
index d8f0290..84bbc7f 100644
--- a/unittests/test_main.c
+++ b/unittests/test_main.c
@@ -21,4 +21,5 @@ int main()
     test_15();
     test_16();
     test_17();
+    test_18();
 }
\ No newline at end of file
diff --git a/unittests/tests.h b/unittests/tests.h
index 810e9a0..4ac1e64 100644
--- a/unittests/tests.h
+++ b/unittests/tests.h
@@ -21,4 +21,5 @@ void test_13();
 void test_14();
 void test_15();
 void test_16();
-void test_17();
\ No newline at end of file
+void test_17();
+void test_18();
\ No newline at end of file