diff --git a/dlls/shlwapi/tests/path.c b/dlls/shlwapi/tests/path.c
index 6c116c9617e..e931d819bdf 100644
--- a/dlls/shlwapi/tests/path.c
+++ b/dlls/shlwapi/tests/path.c
@@ -1072,6 +1072,68 @@ static void test_PathCombineA(void)
     ok(GetLastError() == 0xdeadbeef, "Expected 0xdeadbeef, got %ld\n", GetLastError());
 }
 
+static void test_PathAddBackslash(void)
+{
+    LPSTR str;
+    char path[MAX_PATH];
+    char too_long[LONG_LEN];
+
+    /* try a NULL path */
+    SetLastError(0xdeadbeef);
+    str = PathAddBackslashA(NULL);
+    ok(str == NULL, "Expected str == NULL, got %p\n", str);
+    ok(GetLastError() == 0xdeadbeef, "Expected 0xdeadbeef, got %ld\n", GetLastError());
+
+    /* try an empty path */
+    path[0] = '\0';
+    SetLastError(0xdeadbeef);
+    str = PathAddBackslashA(path);
+    ok(str == (path + lstrlenA(path)), "Expected str to point to end of path, got %p\n", str);
+    ok(lstrlenA(path) == 0, "Expected empty string, got %i\n", lstrlenA(path));
+    ok(GetLastError() == 0xdeadbeef, "Expected 0xdeadbeef, got %ld\n", GetLastError());
+
+    /* try a relative path */
+    lstrcpyA(path, "one\\two");
+    SetLastError(0xdeadbeef);
+    str = PathAddBackslashA(path);
+    ok(str == (path + lstrlenA(path)), "Expected str to point to end of path, got %p\n", str);
+    ok(!lstrcmp(path, "one\\two\\"), "Expected one\\two\\, got %s\n", path);
+    ok(GetLastError() == 0xdeadbeef, "Expected 0xdeadbeef, got %ld\n", GetLastError());
+
+    /* try periods */
+    lstrcpyA(path, "one\\..\\two");
+    SetLastError(0xdeadbeef);
+    str = PathAddBackslashA(path);
+    ok(str == (path + lstrlenA(path)), "Expected str to point to end of path, got %p\n", str);
+    ok(!lstrcmp(path, "one\\..\\two\\"), "Expected one\\..\\two\\, got %s\n", path);
+    ok(GetLastError() == 0xdeadbeef, "Expected 0xdeadbeef, got %ld\n", GetLastError());
+
+    /* try just a space */
+    lstrcpyA(path, " ");
+    SetLastError(0xdeadbeef);
+    str = PathAddBackslashA(path);
+    ok(str == (path + lstrlenA(path)), "Expected str to point to end of path, got %p\n", str);
+    ok(!lstrcmp(path, " \\"), "Expected  \\, got %s\n", path);
+    ok(GetLastError() == 0xdeadbeef, "Expected 0xdeadbeef, got %ld\n", GetLastError());
+
+    /* path already has backslash */
+    lstrcpyA(path, "C:\\one\\");
+    SetLastError(0xdeadbeef);
+    str = PathAddBackslashA(path);
+    ok(str == (path + lstrlenA(path)), "Expected str to point to end of path, got %p\n", str);
+    ok(!lstrcmp(path, "C:\\one\\"), "Expected C:\\one\\, got %s\n", path);
+    ok(GetLastError() == 0xdeadbeef, "Expected 0xdeadbeef, got %ld\n", GetLastError());
+
+    memset(too_long, 'a', LONG_LEN);
+    too_long[LONG_LEN - 1] = '\0';
+
+    /* path is longer than MAX_PATH */
+    SetLastError(0xdeadbeef);
+    str = PathAddBackslashA(too_long);
+    ok(str == NULL, "Expected str == NULL, got %p\n", str);
+    ok(GetLastError() == 0xdeadbeef, "Expected 0xdeadbeef, got %ld\n", GetLastError());
+}
+
 START_TEST(path)
 {
   hShlwapi = LoadLibraryA("shlwapi.dll");
@@ -1090,6 +1152,7 @@ START_TEST(path)
   test_PathCreateFromUrl();
   test_PathIsUrl();
 
+  test_PathAddBackslash();
   test_PathMakePretty();
   test_PathMatchSpec();