diff --git a/lib/checkstring.cpp b/lib/checkstring.cpp
index 16ff8dc0f..6bbfb9098 100644
--- a/lib/checkstring.cpp
+++ b/lib/checkstring.cpp
@@ -66,7 +66,7 @@ void CheckString::stringLiteralWriteError(const Token *tok, const Token *strValu
             s = s.substr(0,13) + "..";
         errmsg += " \"" + s + "\"";
     }
-    errmsg += " directly or indirectly is undefined behaviour";
+    errmsg += " directly or indirectly is undefined behaviour.";
 
     reportError(callstack, Severity::error, "stringLiteralWrite", errmsg);
 }
diff --git a/test/teststring.cpp b/test/teststring.cpp
index 9f229f391..1ef319c20 100644
--- a/test/teststring.cpp
+++ b/test/teststring.cpp
@@ -76,13 +76,13 @@ private:
               "  char *abc = \"abc\";\n"
               "  abc[0] = 'a';\n"
               "}");
-        ASSERT_EQUALS("[test.cpp:3] -> [test.cpp:2]: (error) Modifying string literal \"abc\" directly or indirectly is undefined behaviour\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:3] -> [test.cpp:2]: (error) Modifying string literal \"abc\" directly or indirectly is undefined behaviour.\n", errout.str());
 
         check("void f() {\n"
               "  char *abc = \"abc\";\n"
               "  *abc = 'a';\n"
               "}");
-        ASSERT_EQUALS("[test.cpp:3] -> [test.cpp:2]: (error) Modifying string literal \"abc\" directly or indirectly is undefined behaviour\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:3] -> [test.cpp:2]: (error) Modifying string literal \"abc\" directly or indirectly is undefined behaviour.\n", errout.str());
 
         check("void f() {\n"
               "  QString abc = \"abc\";\n"