diff --git a/dlls/msvcrt/tests/Makefile.in b/dlls/msvcrt/tests/Makefile.in
index 79958ea1243..60348f5bf5d 100644
--- a/dlls/msvcrt/tests/Makefile.in
+++ b/dlls/msvcrt/tests/Makefile.in
@@ -16,6 +16,7 @@ C_SRCS = \
 	file.c \
 	headers.c \
 	heap.c \
+	locale.c \
 	misc.c \
 	printf.c \
 	scanf.c \
diff --git a/dlls/msvcrt/tests/locale.c b/dlls/msvcrt/tests/locale.c
new file mode 100644
index 00000000000..ce44347373b
--- /dev/null
+++ b/dlls/msvcrt/tests/locale.c
@@ -0,0 +1,81 @@
+/*
+ * Unit test suite for locale functions.
+ *
+ * Copyright 2010 Piotr Caban for CodeWeavers
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+#include <locale.h>
+#include "wine/test.h"
+
+static void test_setlocale(void)
+{
+    static const char lc_all[] = "LC_COLLATE=C;LC_CTYPE=C;"
+        "LC_MONETARY=Greek_Greece.1253;LC_NUMERIC=Polish_Poland.1250;LC_TIME=C";
+
+    char *ret, buf[100];
+
+    ret = setlocale(20, "C");
+    ok(ret == NULL, "ret = %s\n", ret);
+
+    ret = setlocale(LC_ALL, "");
+    ok(ret != NULL, "ret == NULL\n");
+
+    ret = setlocale(LC_ALL, "C");
+    ok(!strcmp(ret, "C"), "ret = %s\n", ret);
+
+    ret = setlocale(LC_ALL, NULL);
+    todo_wine ok(!strcmp(ret, "C"), "ret = %s\n", ret);
+
+    if(!setlocale(LC_NUMERIC, "Polish")
+            || !setlocale(LC_NUMERIC, "Greek")
+            || !setlocale(LC_NUMERIC, "German")
+            || !setlocale(LC_NUMERIC, "English")) {
+        win_skip("System with limited locales\n");
+        return;
+    }
+
+    ret = setlocale(LC_NUMERIC, "Polish");
+    ok(!strcmp(ret, "Polish_Poland.1250"), "ret = %s\n", ret);
+
+    ret = setlocale(LC_MONETARY, "Greek");
+    ok(!strcmp(ret, "Greek_Greece.1253"), "ret = %s\n", ret);
+
+    ret = setlocale(LC_ALL, NULL);
+    ok(!strcmp(ret, lc_all), "ret = %s\n", ret);
+
+    strcpy(buf, ret);
+    ret = setlocale(LC_ALL, buf);
+    todo_wine ok(!strcmp(ret, lc_all), "ret = %s\n", ret);
+
+    ret = setlocale(LC_ALL, "German");
+    todo_wine ok(!strcmp(ret, "German_Germany.1252"), "ret = %s\n", ret);
+
+    /* This test shows that _country_synonims table is incorrect */
+    /* It translates "America" to "US" */
+    ret = setlocale(LC_ALL, "America");
+    ok(ret == NULL, "ret = %s\n", ret);
+
+    ret = setlocale(LC_ALL, "US");
+    todo_wine ok(ret != NULL, "ret == NULL\n");
+    if(ret)
+        ok(!strcmp(ret, "English_United States.1252"), "ret = %s\n", ret);
+}
+
+START_TEST(locale)
+{
+    test_setlocale();
+}