diff --git a/extern/icu/source/test/iotest/iotest.cpp b/extern/icu/source/test/iotest/iotest.cpp
index d8952e7191..e4784a6133 100644
--- a/extern/icu/source/test/iotest/iotest.cpp
+++ b/extern/icu/source/test/iotest/iotest.cpp
@@ -682,7 +682,7 @@ static void U_CALLCONV TestStream(void)
     char testStreamBuf[512];
     static const char testStr[] = "\x42\x65\x67\x69\x6E\x6E\x69\x6E\x67\x20\x6F\x66\x20\x74\x65\x73\x74\x20\x73\x74\x72\x31\x20\x20\x20\x3C\x3C\x32\x31\x20" UTF8_NEW_LINE "\x20\x55\x54\x46\x2D\x38\x20\xCE\xBC\xF0\x90\x80\x81\xF0\x90\x80\x82";
     ostrstream outTestStream(testStreamBuf, sizeof(testStreamBuf));
-    istrstream inTestStream("\x20\x74\x48\x69\x73\xCE\xBC\xE2\x80\x82\x20\x6D\x75\x20\x77\x6F\x72\x6C\x64", 0);
+    istrstream inTestStream((const char*) "\x20\x74\x48\x69\x73\xCE\xBC\xE2\x80\x82\x20\x6D\x75\x20\x77\x6F\x72\x6C\x64", 0);
     const UChar thisMu[] = { 0x74, 0x48, 0x69, 0x73, 0x3BC, 0};
     const UChar mu[] = { 0x6D, 0x75, 0};
     UnicodeString str1 = UNICODE_STRING_SIMPLE("str1");