diff --git a/icu4c/source/test/fuzzer/collator_rulebased_fuzzer.cpp b/icu4c/source/test/fuzzer/collator_rulebased_fuzzer.cpp
index 63cf385a1c87..ee6d63980c0e 100644
--- a/icu4c/source/test/fuzzer/collator_rulebased_fuzzer.cpp
+++ b/icu4c/source/test/fuzzer/collator_rulebased_fuzzer.cpp
@@ -18,9 +18,19 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
       size = 2000;
   }
 
-  size_t unistr_size = size/2;
+  // Use all bytes: allocate enough char16_t for all bytes, rounded up
+  size_t unistr_size = (size + 1) / 2;  // Round up to handle odd size
   std::unique_ptr<char16_t[]> fuzzbuff(new char16_t[unistr_size]);
-  std::memcpy(fuzzbuff.get(), data, unistr_size * 2);
+  // Copy all bytes, zero-initialize any remaining byte in the last char16_t
+  if (size > 0) {
+    std::memcpy(fuzzbuff.get(), data, size);
+    // If size is odd, zero the last byte of the last char16_t
+    if (size % 2 == 1) {
+      // Cast to uint8_t* to access individual bytes
+      uint8_t* buffer_bytes = reinterpret_cast<uint8_t*>(fuzzbuff.get());
+      buffer_bytes[size] = 0;  // Zero the unused byte in last char16_t
+    }
+  }
   icu::UnicodeString fuzzstr(false, fuzzbuff.get(), unistr_size);
 
   icu::LocalPointer<icu::RuleBasedCollator> col1(
@@ -28,18 +38,24 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
 
   if (U_SUCCESS(status)) {
       col1->getVariableTop(status);
-      status = U_ZERO_ERROR;
+      if (U_FAILURE(status)) return 0;
+      
       icu::CollationKey key;
       col1->getCollationKey(fuzzstr, key, status);
-      status = U_ZERO_ERROR;
+      if (U_FAILURE(status)) return 0;
+      
       icu::LocalPointer<icu::UnicodeSet> tailoredSet(col1->getTailoredSet(status));
-      status = U_ZERO_ERROR;
+      if (U_FAILURE(status)) return 0;
+      
       col1->getLocale(ULOC_ACTUAL_LOCALE, status);
-      status = U_ZERO_ERROR;
+      if (U_FAILURE(status)) return 0;
+      
       col1->getLocale(ULOC_VALID_LOCALE, status);
+      if (U_FAILURE(status)) return 0;
+      
       col1->getMaxVariable();
       col1->getStrength();
       col1->getSortKey(fuzzstr, nullptr, 0);
   }
   return 0;
-}
+}
\ No newline at end of file