diff --git a/icu4c/source/test/cintltst/cloctst.c b/icu4c/source/test/cintltst/cloctst.c
index 161a270959..7e90a7ebf9 100644
--- a/icu4c/source/test/cintltst/cloctst.c
+++ b/icu4c/source/test/cintltst/cloctst.c
@@ -1143,6 +1143,72 @@ static void TestObsoleteNames(void)
 
 }
 
+/**
+ * List of all valid ISO 4217 codes.  Include historical as well as
+ * current codes.  This list must be updated to include any new
+ * currencies added to ICU.  We check locale data against this list to
+ * ensure that invalid currency codes are not added.
+ */
+static const char* ISO_4217[] = {
+    /* Modern currencies */
+    "ADP", "AED", "AFN", "ALL", "AMD", "ANG", "AOA", "ARS", "AUD", "AWG",
+    "AZM", "BAM", "BBD", "BDT", "BGL", "BGN", "BHD", "BIF", "BMD", "BND",
+    "BOB", "BOV", "BRL", "BSD", "BTN", "BWP", "BYR", "BZD", "CAD", "CDF",
+    "CHF", "CLF", "CLP", "CNY", "COP", "CRC", "CUP", "CVE", "CYP", "CZK",
+    "DJF", "DKK", "DOP", "DZD", "ECS", "ECV", "EEK", "EGP", "ERN", "ETB",
+    "EUR", "FJD", "FKP", "GBP", "GEL", "GHC", "GIP", "GMD", "GNF", "GTQ",
+    "GWP", "GYD", "HKD", "HNL", "HRK", "HTG", "HUF", "IDR", "ILS", "INR",
+    "IQD", "IRR", "ISK", "JMD", "JOD", "JPY", "KES", "KGS", "KHR", "KMF",
+    "KPW", "KRW", "KWD", "KYD", "KZT", "LAK", "LBP", "LKR", "LRD", "LSL",
+    "LTL", "LVL", "LYD", "MAD", "MDL", "MGF", "MKD", "MMK", "MNT", "MOP",
+    "MRO", "MTL", "MUR", "MVR", "MWK", "MXN", "MXV", "MYR", "MZM", "NAD",
+    "NGN", "NIO", "NOK", "NPR", "NZD", "OMR", "PAB", "PEN", "PGK", "PHP",
+    "PKR", "PLN", "PYG", "QAR", "ROL", "RUB", "RUR", "RWF", "SAR", "SBD",
+    "SCR", "SDD", "SEK", "SGD", "SHP", "SIT", "SKK", "SLL", "SOS", "SRG",
+    "STD", "SVC", "SYP", "SZL", "THB", "TJS", "TMM", "TND", "TOP", "TRL",
+    "TTD", "TWD", "TZS", "UAH", "UGX", "USD", "USN", "USS", "UYU", "UZS",
+    "VEB", "VND", "VUV", "WST", "XAF", "XCD", "XOF", "XPF", "YER", "YUM",
+    "ZAR", "ZMK", "ZWD",
+
+    /* From ISO 4217:1981 */
+    "AFA", "AOK", "AON", "ARP", "ATS", "BEC", "BEF", "BEL", "BOP", "BRC",
+    "BRR", "BUK", "CSK", "DDM", "DEM", "ESA", "ESB", "ESP", "FIM", "FRF",
+    "GEK", "GNS", "GQE", "GRD", "IEP", "ITL", "LSM", "LUF", "MLF", "MTP",
+    "MXP", "NIC", "NLG", "PES", "PLZ", "PTE", "SDP", "SUR", "TPE", "UAK",
+    "UGS", "UYP", "XAU", "XBA", "XBB", "XBC", "XBD", "XDR", "XEU", "XXX",
+    "YDD", "YUD", "ZAL", "ZRZ",
+
+    /* Obsolete currencies, less well-documented */
+    "AOR", /* ANGOLA Kwanza Readjustado */
+    "ARA", /* ARGENTINA Austral */
+    "BAD", /* BOSNIA Bosnian Dinar */
+    "BYB", /* BELARUS Belarussian Ruble */
+    "HRD", /* CROATIA Croatian Dinar */
+    "PEI", /* PERU Inti */
+    "TJR", /* TAJIKISTAN Tajik Ruble */
+    "YUN"  /* YUGOSLAVIA Yugoslavian Dinar */
+
+    /* Invalid codes that are sometimes seen:
+       "DRP",
+       "ECU",
+       "KIS",
+       "NIS",
+       "RMB",
+    */
+};
+
+static const int32_t ISO_4217_COUNT = sizeof(ISO_4217)/sizeof(ISO_4217[0]);
+
+static UBool isValidISO4217(const char* curr) {
+    int32_t i;
+    for (i=0; i<ISO_4217_COUNT; ++i) {
+        if (strcmp(curr, ISO_4217[i]) == 0) {
+            return TRUE;
+        }
+    }
+    return FALSE;
+}
+
 static void
 TestKeyInRootRecursive(UResourceBundle *root, UResourceBundle *currentBundle, const char *locale) {
     UErrorCode errorCode = U_ZERO_ERROR;
@@ -1172,10 +1238,18 @@ TestKeyInRootRecursive(UResourceBundle *root, UResourceBundle *currentBundle, co
                     break;
                 }
                 else {*/
-                    if (subBundleKey == NULL
+                    const char* bundleKey = ures_getKey(currentBundle);
+                    if (bundleKey != NULL &&
+                        strcmp(bundleKey, "Currencies") == 0) {
+                        if (!isValidISO4217(subBundleKey)) {
+
+                            log_data_err("Unknown ISO 4217 code \"%s\" in locale \"%s\"; see cloctst.c/ISO_4217[]\n",
+                                         subBundleKey,
+                                         locale);
+                        }
+                    } else if (subBundleKey == NULL
                         || (strcmp(subBundleKey, "TransliterateLATIN") != 0 /* Ignore these special cases */
-                        && strcmp(subBundleKey, "BreakDictionaryData") != 0
-                        && strcmp(ures_getKey(currentBundle), "Currencies") != 0))
+                        && strcmp(subBundleKey, "BreakDictionaryData") != 0))
                     {
                         log_data_err("Can't open a resource with key \"%s\" in \"%s\" from root for locale \"%s\"\n",
                                 subBundleKey,