diff --git a/icu4c/source/common/iculserv.cpp b/icu4c/source/common/iculserv.cpp
index 6bb908a8d20..29d2de08221 100644
--- a/icu4c/source/common/iculserv.cpp
+++ b/icu4c/source/common/iculserv.cpp
@@ -661,7 +661,7 @@ ICUResourceBundleFactory::handleCreate(const Locale& loc, int32_t /* kind */, co
         char pkg[20];
         int32_t length;
         length=_bundleName.extract(0, INT32_MAX, pkg, (int32_t)sizeof(pkg), US_INV);
-        if(length>=sizeof(pkg)) {
+        if(length>=(int32_t)sizeof(pkg)) {
             return NULL;
         }
         return new ResourceBundle(pkg, loc, status);
diff --git a/icu4c/source/common/rbbiscan.cpp b/icu4c/source/common/rbbiscan.cpp
index 3953329623b..13c44c42ba0 100644
--- a/icu4c/source/common/rbbiscan.cpp
+++ b/icu4c/source/common/rbbiscan.cpp
@@ -1061,13 +1061,15 @@ void RBBIRuleScanner::parse() {
 //  printNodeStack     for debugging...
 //
 //---------------------------------------------------------------------------------
-void RBBIRuleScanner::printNodeStack(const char *title) {
 #ifdef RBBI_DEBUG
+void RBBIRuleScanner::printNodeStack(const char *) {}
+#else
+void RBBIRuleScanner::printNodeStack(const char *title) {
     int i;
     RBBIDebugPrintf("%s.  Dumping node stack...\n", title);
     for (i=fNodeStackPtr; i>0; i--) {fNodeStack[i]->printTree(TRUE);}
-#endif
 }
+#endif
 
 
 
diff --git a/icu4c/source/i18n/dcfmtsym.cpp b/icu4c/source/i18n/dcfmtsym.cpp
index 74d658d7d4e..d9b4d484d82 100644
--- a/icu4c/source/i18n/dcfmtsym.cpp
+++ b/icu4c/source/i18n/dcfmtsym.cpp
@@ -208,14 +208,12 @@ DecimalFormatSymbols::initialize(const UChar** numberElements, int32_t *numberEl
         {kPlusSignSymbol, 11},
         {kMonetarySeparatorSymbol, 0}
     };
-    static const int32_t TYPE_MAPPING_LEN = (int32_t)(sizeof(TYPE_MAPPING)/sizeof(TYPE_MAPPING[0]));
     int32_t idx;
-    if (numberElementsLength > TYPE_MAPPING_LEN) {
-        numberElementsLength = TYPE_MAPPING_LEN;
-    }
 
-    for (idx = 0; idx < numberElementsLength; idx++) {
-        fSymbols[TYPE_MAPPING[idx][0]].setTo(TRUE, numberElements[TYPE_MAPPING[idx][1]], numberElementsStrLen[TYPE_MAPPING[idx][1]]);
+    for (idx = 0; idx < (int32_t)(sizeof(TYPE_MAPPING)/sizeof(TYPE_MAPPING[0])); idx++) {
+        if (TYPE_MAPPING[idx][1] < numberElementsLength) {
+            fSymbols[TYPE_MAPPING[idx][0]].setTo(TRUE, numberElements[TYPE_MAPPING[idx][1]], numberElementsStrLen[TYPE_MAPPING[idx][1]]);
+        }
     }
 
     // Default values until it's set later on.
diff --git a/icu4c/source/i18n/rbnf.cpp b/icu4c/source/i18n/rbnf.cpp
index 957fc5cf976..dbb8cf5b366 100644
--- a/icu4c/source/i18n/rbnf.cpp
+++ b/icu4c/source/i18n/rbnf.cpp
@@ -900,7 +900,7 @@ RuleBasedNumberFormat::getRuleSetDisplayNameLocale(int32_t index, UErrorCode& st
         if (cap > 64) {
             bp = new char[cap];
         }
-        int32_t len = name.extract(0, name.length(), bp, cap, UnicodeString::kInvariant);
+        name.extract(0, name.length(), bp, cap, UnicodeString::kInvariant);
         Locale retLocale(bp);
         if (bp != buffer) {
             delete[] bp;
diff --git a/icu4c/source/i18n/tridpars.cpp b/icu4c/source/i18n/tridpars.cpp
index 9b6326d8d54..3aadb70c0d9 100644
--- a/icu4c/source/i18n/tridpars.cpp
+++ b/icu4c/source/i18n/tridpars.cpp
@@ -652,7 +652,6 @@ void TransliteratorIDParser::registerSpecialInverse(const UnicodeString& target,
     umtx_init(&LOCK);
     Mutex lock(&LOCK);
 
-    UErrorCode ec = U_ZERO_ERROR;
     SPECIAL_INVERSES->put(target, new UnicodeString(inverseTarget), status);
     if (bidirectional) {
         SPECIAL_INVERSES->put(inverseTarget, new UnicodeString(target), status);