--- source/common/ustring.cpp
+++ source/common/ustring.cpp
@@ -1486,7 +1486,7 @@
 */
 
 #define STRING_HASH(TYPE, STR, STRLEN, DEREF) \
-    int32_t hash = 0;                         \
+    uint32_t hash = 0;                         \
     const TYPE *p = (const TYPE*) STR;        \
     if (p != NULL) {                          \
         int32_t len = (int32_t)(STRLEN);      \
@@ -1497,7 +1497,7 @@
             p += inc;                         \
         }                                     \
     }                                         \
-    return hash
+    return static_cast<int32_t>(hash)
 
 /* Used by UnicodeString to compute its hashcode - Not public API. */
 U_CAPI int32_t U_EXPORT2