diff --git a/icu4c/source/common/umapfile.cpp b/icu4c/source/common/umapfile.cpp
index ab8829d8c38..3ba0251df9c 100644
--- a/icu4c/source/common/umapfile.cpp
+++ b/icu4c/source/common/umapfile.cpp
@@ -238,7 +238,12 @@ typedef HANDLE MemoryMap;
         pData->pHeader=(const DataHeader *)data;
         pData->mapAddr = data;
 #if U_PLATFORM == U_PF_IPHONE || U_PLATFORM == U_PF_ANDROID
+    // Apparently supported from Android 23 and higher:
+    //   https://github.com/ggml-org/llama.cpp/pull/3631
+    // Checking for the flag itself is safer than checking for __ANDROID_API__.
+#   ifdef POSIX_MADV_RANDOM
         posix_madvise(data, length, POSIX_MADV_RANDOM);
+#   endif
 #endif
         return true;
     }