diff --git a/dlls/kernel/tests/file.c b/dlls/kernel/tests/file.c
index dd1e06ca595..ee4b10b60c6 100644
--- a/dlls/kernel/tests/file.c
+++ b/dlls/kernel/tests/file.c
@@ -618,6 +618,23 @@ static void test_CreateFileW(void)
     ok(ret, "DeleteFileW: error %ld\n", GetLastError());
 }
 
+
+static void test_GetTempFileNameA() {
+    UINT result;
+    char out[MAX_PATH];
+    char *expected = "c:\\windows\\abc2.tmp";
+
+    /* this test may depend on the config file settings */
+    result = GetTempFileNameA("C:", "abc", 1, out);
+    ok( result != 0, "GetTempFileNameA: error %ld\n", GetLastError() );
+    ok( ((out[0] == 'C') && (out[1] == ':')) && (out[2] == '\\'), "GetTempFileNameA: first three characters should be C:\\, string was actually %s", out );
+
+    result = GetTempFileNameA("c:\\windows\\", "abc", 2, out);
+    ok( result != 0, "GetTempFileNameA: error %ld\n", GetLastError() );
+    ok( strcasecmp( out, expected ) == 0, "GetTempFileNameA: Unexpected output \"%s\" vs \"%s\"\n", out, expected );
+}
+
+
 static void test_DeleteFileA( void )
 {
     BOOL ret;
@@ -972,6 +989,7 @@ START_TEST(file)
     test__llopen(  );
     test__lread(  );
     test__lwrite(  );
+    test_GetTempFileNameA();
     test_CopyFileA();
     test_CopyFileW();
     test_CreateFileA();
diff --git a/files/file.c b/files/file.c
index ff3cf60b862..9b4a21c8d74 100644
--- a/files/file.c
+++ b/files/file.c
@@ -905,7 +905,7 @@ UINT WINAPI GetTempFileNameA( LPCSTR path, LPCSTR prefix, UINT unique,
 UINT WINAPI GetTempFileNameW( LPCWSTR path, LPCWSTR prefix, UINT unique,
                                   LPWSTR buffer )
 {
-    static const WCHAR formatW[] = {'%','0','4','x','.','t','m','p',0};
+    static const WCHAR formatW[] = {'%','x','.','t','m','p',0};
 
     DOS_FULL_NAME full_name;
     int i;
@@ -920,9 +920,8 @@ UINT WINAPI GetTempFileNameW( LPCWSTR path, LPCWSTR prefix, UINT unique,
     strcpyW( buffer, path );
     p = buffer + strlenW(buffer);
 
-    /* add a \, if there isn't one and path is more than just the drive letter ... */
-    if ( !((strlenW(buffer) == 2) && (buffer[1] == ':'))
-       && ((p == buffer) || (p[-1] != '\\'))) *p++ = '\\';
+    /* add a \, if there isn't one  */
+    if ((p == buffer) || (p[-1] != '\\')) *p++ = '\\';
 
     for (i = 3; (i > 0) && (*prefix); i--) *p++ = *prefix++;