diff --git a/icu4c/source/test/cintltst/cmsgtst.c b/icu4c/source/test/cintltst/cmsgtst.c
index 5dc8ac7394c..c41eee59557 100644
--- a/icu4c/source/test/cintltst/cmsgtst.c
+++ b/icu4c/source/test/cintltst/cmsgtst.c
@@ -61,12 +61,12 @@ static void InitStrings( void )
         return;
 
     for (i=0; i < cnt_testCases; i++ ) {
-        uint32_t strSize = strlen(txt_testCasePatterns[i]) + 1;
+        uint32_t strSize = (uint32_t)strlen(txt_testCasePatterns[i]) + 1;
         testCasePatterns[i]=(UChar*)malloc(sizeof(UChar) * strSize);
         u_uastrncpy(testCasePatterns[i], txt_testCasePatterns[i], strSize);
     }
     for (i=0; i < cnt_testCases; i++ ) {
-        uint32_t strSize = strlen(txt_testResultStrings[i]) + 1;
+        uint32_t strSize = (uint32_t)strlen(txt_testResultStrings[i]) + 1;
         testResultStrings[i] = (UChar*)malloc(sizeof(UChar) * strSize);
         u_uastrncpy(testResultStrings[i], txt_testResultStrings[i], strSize);
     }
diff --git a/icu4c/source/test/cintltst/usrchtst.c b/icu4c/source/test/cintltst/usrchtst.c
index 79550ec7607..a5f8127c7d8 100644
--- a/icu4c/source/test/cintltst/usrchtst.c
+++ b/icu4c/source/test/cintltst/usrchtst.c
@@ -142,6 +142,7 @@ static char *toCharString(const UChar* unichars)
         }
         else {
             sprintf(temp, "\\u%04x", ch);
+            temp += 6; /* \uxxxx */
         }
     }
     *temp = 0;
diff --git a/icu4c/source/test/intltest/convtest.cpp b/icu4c/source/test/intltest/convtest.cpp
index 7b7b69afe6e..791ed3c76c3 100644
--- a/icu4c/source/test/intltest/convtest.cpp
+++ b/icu4c/source/test/intltest/convtest.cpp
@@ -1051,7 +1051,7 @@ ConversionTest::FromUnicodeCase(ConversionCase &cc, UConverterFromUCallback call
     // set the subchar
     int32_t length;
 
-    if((length=strlen(cc.subchar))!=0) {
+    if((length=(int32_t)strlen(cc.subchar))!=0) {
         ucnv_setSubstChars(cnv, cc.subchar, (int8_t)length, &errorCode);
         if(U_FAILURE(errorCode)) {
             errln("fromUnicode[%d](%s cb=\"%s\" fb=%d flush=%d) ucnv_setSubChars() failed - %s",
diff --git a/icu4c/source/test/intltest/srchtest.cpp b/icu4c/source/test/intltest/srchtest.cpp
index c7b08ae44ca..a673f253014 100644
--- a/icu4c/source/test/intltest/srchtest.cpp
+++ b/icu4c/source/test/intltest/srchtest.cpp
@@ -194,33 +194,19 @@ BreakIterator * StringSearchTest::getBreakIterator(const char *breaker)
 
 char * StringSearchTest::toCharString(const UnicodeString &text)
 {
-           UChar  unichars[512];
     static char   result[1024];
-           int    count  = 0;
            int    index  = 0;
+           int    count  = 0;
            int    length = text.length();
 
-    text.extract(0, text.length(), unichars, 0);
-
     for (; count < length; count ++) {
-        UChar ch = unichars[count];
+        UChar ch = text[count];
         if (ch >= 0x20 && ch <= 0x7e) {
             result[index ++] = (char)ch;
         }
         else {
-            char digit[5];
-            int  zerosize;
-            result[index ++] = '\\';
-            result[index ++] = 'u';
-            sprintf(digit, "%x", ch);
-            zerosize = 4 - strlen(digit);
-            while (zerosize != 0) {
-                result[index ++] = '0';
-                zerosize --;
-            }
-            result[index] = 0;
-            strcat(result, digit);
-            index += strlen(digit);
+            sprintf(result+index, "\\u%04x", ch);
+            index += 6; /* \uxxxx */
         }
     }
     result[index] = 0;
diff --git a/icu4c/source/test/intltest/svccoll.cpp b/icu4c/source/test/intltest/svccoll.cpp
index 7de6e3d3b4b..1274fbd914f 100644
--- a/icu4c/source/test/intltest/svccoll.cpp
+++ b/icu4c/source/test/intltest/svccoll.cpp
@@ -266,7 +266,7 @@ public:
   {
     CollatorInfo** p;
     for (p = info; *p; ++p) {}
-    count = p - info;
+    count = (int32_t)(p - info);
   }
 
   ~TestFactory() {
diff --git a/icu4c/source/test/intltest/textfile.cpp b/icu4c/source/test/intltest/textfile.cpp
index 2765f2b9257..fe193b0fcbd 100644
--- a/icu4c/source/test/intltest/textfile.cpp
+++ b/icu4c/source/test/intltest/textfile.cpp
@@ -50,7 +50,7 @@ TextFile::TextFile(const char* _name, const char* _encoding, UErrorCode& ec) :
     if (U_FAILURE(ec)) {
         return;
     }
-    if (!ensureCapacity(uprv_strlen(testDir) + uprv_strlen(name) + 1)) {
+    if (!ensureCapacity((int32_t)(uprv_strlen(testDir) + uprv_strlen(name) + 1))) {
         ec = U_MEMORY_ALLOCATION_ERROR;
         return;
     }