diff --git a/src/openrct2/network/Network.cpp b/src/openrct2/network/Network.cpp
index 2aaf8586a1..d3c8e4562c 100644
--- a/src/openrct2/network/Network.cpp
+++ b/src/openrct2/network/Network.cpp
@@ -1625,9 +1625,10 @@ uint8_t* Network::save_for_network(size_t& out_size, const std::vector<const Obj
     const void* data = ms.GetData();
     int32_t size = ms.GetLength();
 
-    uint8_t* compressed = util_zlib_deflate(static_cast<const uint8_t*>(data), size, &out_size);
-    if (compressed != nullptr)
+    auto compressed = util_zlib_deflate(static_cast<const uint8_t*>(data), size);
+    if (compressed != std::nullopt)
     {
+        out_size = compressed->size();
         header = reinterpret_cast<uint8_t*>(_strdup("open2_sv6_zlib"));
         size_t header_len = strlen(reinterpret_cast<char*>(header)) + 1; // account for null terminator
         header = static_cast<uint8_t*>(realloc(header, header_len + out_size));
@@ -1637,11 +1638,10 @@ uint8_t* Network::save_for_network(size_t& out_size, const std::vector<const Obj
         }
         else
         {
-            std::memcpy(&header[header_len], compressed, out_size);
+            std::memcpy(&header[header_len], compressed->data(), out_size);
             out_size += header_len;
             log_verbose("Sending map of size %u bytes, compressed to %u bytes", size, out_size);
         }
-        free(compressed);
     }
     else
     {
diff --git a/src/openrct2/util/Util.cpp b/src/openrct2/util/Util.cpp
index 46726c5fa1..d7e513e725 100644
--- a/src/openrct2/util/Util.cpp
+++ b/src/openrct2/util/Util.cpp
@@ -586,34 +586,30 @@ uint8_t* util_zlib_inflate(uint8_t* data, size_t data_in_size, size_t* data_out_
  * @brief Deflates input using zlib
  * @param data Data to be compressed
  * @param data_in_size Size of data to be compressed
- * @param data_out_size Pointer to a variable where output size will be written
- * @return Returns a pointer to memory holding compressed data or NULL on failure.
- * @note It is caller's responsibility to free() the returned pointer once done with it.
+ * @return Returns an optional std::vector of bytes, which is equal to std::nullopt when deflate has failed
  */
-uint8_t* util_zlib_deflate(const uint8_t* data, size_t data_in_size, size_t* data_out_size)
+std::optional<std::vector<uint8_t>> util_zlib_deflate(const uint8_t* data, size_t data_in_size)
 {
     int32_t ret = Z_OK;
-    uLongf out_size = static_cast<uLongf>(*data_out_size);
+    uLongf out_size = 0;
     uLong buffer_size = compressBound(static_cast<uLong>(data_in_size));
-    uint8_t* buffer = static_cast<uint8_t*>(malloc(buffer_size));
+    std::vector<uint8_t> buffer(buffer_size);
     do
     {
         if (ret == Z_BUF_ERROR)
         {
             buffer_size *= 2;
             out_size = buffer_size;
-            buffer = static_cast<uint8_t*>(realloc(buffer, buffer_size));
+            buffer.resize(buffer_size);
         }
         else if (ret == Z_STREAM_ERROR)
         {
             log_error("Your build is shipped with broken zlib. Please use the official build.");
-            free(buffer);
-            return nullptr;
+            return std::nullopt;
         }
-        ret = compress(buffer, &out_size, data, static_cast<uLong>(data_in_size));
+        ret = compress(buffer.data(), &out_size, data, static_cast<uLong>(data_in_size));
     } while (ret != Z_OK);
-    *data_out_size = out_size;
-    buffer = static_cast<uint8_t*>(realloc(buffer, *data_out_size));
+    buffer.resize(out_size);
     return buffer;
 }
 
diff --git a/src/openrct2/util/Util.h b/src/openrct2/util/Util.h
index ec046e8036..997de6e03b 100644
--- a/src/openrct2/util/Util.h
+++ b/src/openrct2/util/Util.h
@@ -14,6 +14,8 @@
 
 #include <cstdio>
 #include <ctime>
+#include <optional>
+#include <vector>
 
 int32_t squaredmetres_to_squaredfeet(int32_t squaredMetres);
 int32_t metres_to_feet(int32_t metres);
@@ -52,7 +54,7 @@ bool str_is_null_or_empty(const char* str);
 
 uint32_t util_rand();
 
-uint8_t* util_zlib_deflate(const uint8_t* data, size_t data_in_size, size_t* data_out_size);
+std::optional<std::vector<uint8_t>> util_zlib_deflate(const uint8_t* data, size_t data_in_size);
 uint8_t* util_zlib_inflate(uint8_t* data, size_t data_in_size, size_t* data_out_size);
 bool util_gzip_compress(FILE* source, FILE* dest);