diff --git a/dlls/msvcrt/tests/string.c b/dlls/msvcrt/tests/string.c
index b2703665992..2e963dc8ade 100644
--- a/dlls/msvcrt/tests/string.c
+++ b/dlls/msvcrt/tests/string.c
@@ -3346,6 +3346,49 @@ static void test__memicmp_l(void)
     ok(errno == 0xdeadbeef, "errno is %d, expected 0xdeadbeef\n", errno);
 }
 
+static void test__strupr(void)
+{
+    const char str[] = "123";
+    char str2[4];
+    char *mem, *p;
+    DWORD prot;
+
+    mem = VirtualAlloc(NULL, sizeof(str), MEM_COMMIT, PAGE_READWRITE);
+    ok(mem != NULL, "VirtualAlloc failed\n");
+    memcpy(mem, str, sizeof(str));
+    ok(VirtualProtect(mem, sizeof(str), PAGE_READONLY, &prot), "VirtualProtect failed\n");
+
+    strcpy(str2, "aBc");
+    p = _strupr(str2);
+    ok(p == str2, "_strupr returned %p\n", p);
+    ok(!strcmp(str2, "ABC"), "str2 = %s\n", str2);
+
+    p = _strupr(mem);
+    ok(p == mem, "_strupr returned %p\n", p);
+    ok(!strcmp(mem, "123"), "mem = %s\n", mem);
+
+    if(!setlocale(LC_ALL, "english")) {
+        VirtualFree(mem, sizeof(str), MEM_RELEASE);
+        win_skip("English locale _strupr tests\n");
+        return;
+    }
+
+    strcpy(str2, "aBc");
+    p = _strupr(str2);
+    ok(p == str2, "_strupr returned %p\n", p);
+    ok(!strcmp(str2, "ABC"), "str2 = %s\n", str2);
+
+    if (0) /* crashes on Windows */
+    {
+        p = _strupr(mem);
+        ok(p == mem, "_strupr returned %p\n", p);
+        ok(!strcmp(mem, "123"), "mem = %s\n", mem);
+    }
+
+    setlocale(LC_ALL, "C");
+    VirtualFree(mem, sizeof(str), MEM_RELEASE);
+}
+
 START_TEST(string)
 {
     char mem[100];
@@ -3468,4 +3511,5 @@ START_TEST(string)
     test__ismbclx();
     test__memicmp();
     test__memicmp_l();
+    test__strupr();
 }