diff --git a/icu4c/source/test/cintltst/cmsccoll.c b/icu4c/source/test/cintltst/cmsccoll.c
index 036002638ed..f86225b8c06 100644
--- a/icu4c/source/test/cintltst/cmsccoll.c
+++ b/icu4c/source/test/cintltst/cmsccoll.c
@@ -4630,6 +4630,23 @@ static void TestTailorNULL( void ) {
     ucol_close(coll);
 }
 
+static void
+TestThaiSortKey(void)
+{
+  UChar yamakan = 0x0E4E;
+  UErrorCode status = U_ZERO_ERROR;
+  UCollator *coll = ucol_open("th", &status);
+  uint8_t key[256];
+  int32_t keyLen = ucol_getSortKey(coll, &yamakan, 1, key, 256);
+  uint8_t expectedKey[256] = { 0x01, 0xd9, 0xb2, 0x01, 0x05, 0x00 };
+
+  if(strcmp((char *)key, (char *)expectedKey)) {
+    log_err("Yamakan key is different from ICU 262!\n");
+  }
+
+
+}
+
 #define TEST(x) addTest(root, &x, "tscoll/cmsccoll/" # x)
 
 void addMiscCollTest(TestNode** root)
@@ -4693,6 +4710,7 @@ void addMiscCollTest(TestNode** root)
     TEST(TestBeforeTightening);
     /*TEST(TestMoreBefore);*/
     TEST(TestTailorNULL);
+    TEST(TestThaiSortKey);
 }
 
 #endif /* #if !UCONFIG_NO_COLLATION */