diff --git a/icu4c/source/test/fuzzer/list_format_fuzzer.cpp b/icu4c/source/test/fuzzer/list_format_fuzzer.cpp
index e6b5de3d0491..4821e8516c17 100644
--- a/icu4c/source/test/fuzzer/list_format_fuzzer.cpp
+++ b/icu4c/source/test/fuzzer/list_format_fuzzer.cpp
@@ -22,19 +22,28 @@ void TestFormat(icu::ListFormatter* listFormat, const icu::UnicodeString* items)
 }
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
     uint16_t rnd;
-    UListFormatterType type;
-    UListFormatterWidth width;
-    if (size < sizeof(rnd) + sizeof(type) + sizeof(width)) return 0;
+    int32_t raw_type;
+    int32_t raw_width;
+    if (size < sizeof(rnd) + sizeof(raw_type) + sizeof(raw_width)) return 0;
     icu::StringPiece fuzzData(reinterpret_cast<const char *>(data), size);
 
     std::memcpy(&rnd, fuzzData.data(), sizeof(rnd));
     icu::Locale locale = GetRandomLocale(rnd);
     fuzzData.remove_prefix(sizeof(rnd));
 
-    std::memcpy(&type, fuzzData.data(), sizeof(type));
-    fuzzData.remove_prefix(sizeof(type));
-    std::memcpy(&width, fuzzData.data(), sizeof(width));
-    fuzzData.remove_prefix(sizeof(width));
+    std::memcpy(&raw_type, fuzzData.data(), sizeof(raw_type));
+    fuzzData.remove_prefix(sizeof(raw_type));
+    std::memcpy(&raw_width, fuzzData.data(), sizeof(raw_width));
+    fuzzData.remove_prefix(sizeof(raw_width));
+
+    // Ensure non-negative before modulo.
+    int32_t type_index = raw_type < 0 ? -raw_type : raw_type;
+    int32_t width_index = raw_width < 0 ? -raw_width : raw_width;
+
+    UListFormatterType type = static_cast<UListFormatterType>(
+        type_index % (static_cast<int>(ULISTFMT_TYPE_UNITS) + 1));
+    UListFormatterWidth width = static_cast<UListFormatterWidth>(
+        width_index % (static_cast<int>(ULISTFMT_WIDTH_NARROW) + 1));
 
     size_t len = fuzzData.size() / sizeof(char16_t);
     icu::UnicodeString text(false, reinterpret_cast<const char16_t*>(fuzzData.data()), len);
@@ -54,16 +63,5 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
         TestFormat(listFormat.get(), items);
     }
 
-    status = U_ZERO_ERROR;
-    type = static_cast<UListFormatterType>(
-        static_cast<int>(type) % (static_cast<int>(ULISTFMT_TYPE_UNITS) + 1));
-    width = static_cast<UListFormatterWidth>(
-        static_cast<int>(width) % (static_cast<int>(ULISTFMT_WIDTH_NARROW) + 1));
-    listFormat.reset(
-        icu::ListFormatter::createInstance(locale, type, width, status));
-    if (U_SUCCESS(status)) {
-        TestFormat(listFormat.get(), items);
-    }
-
     return EXIT_SUCCESS;
 }