diff --git a/src/tools/zlibutil.cpp b/src/tools/zlibutil.cpp
index f9e3bdb..184f05b 100644
--- a/src/tools/zlibutil.cpp
+++ b/src/tools/zlibutil.cpp
@@ -28,6 +28,7 @@
 #include "../lib/cli.hpp"
 #include "../lib/file.hpp"
 #include "../lib/zlibutil.hpp"
+#include "../lib/error.hpp"
 
 #define EXIT_SUCCESS 0
 #define EXIT_RUNTIME 1
@@ -112,14 +113,18 @@ int main(int argc, char* argv[]) {
         return EXIT_RUNTIME;
     }
     File* file = filePointer.value;
-    File *writeFile;
+    File* writeFile;
 
     if (cliParser.getFlag("decompress").value) {
-        std::vector<uint8_t> bytes = file->read(file->size.value).value; // this is what you get from lib/file IIRC
-        std::vector<char> differentBytes = std::vector<char>(bytes.begin(), bytes.end());
+        std::vector<uint8_t> bytes = file->read(file->size.value).value;
 
-        std::vector<char> compressed = decompressData(differentBytes.data(), file->size.value);
-        std::vector<unsigned char> unsigneddata = std::vector<unsigned char>(compressed.begin(), compressed.end());
+        ErrorOr<std::vector<uint8_t>> decompressed = zlib::decompressData(bytes);
+        if (decompressed.isError) {
+            std::cout << "Error: Failed to decompress: " << filename << std::endl;
+            delete file;
+            // not cleaning up writeFile here bc it hasn't been created
+            return EXIT_RUNTIME;
+        }
 
         std::string outFilename;
         if (filename.length() > 3 && filename.rfind(".zz") == filename.length()-3) {
@@ -128,16 +133,23 @@ int main(int argc, char* argv[]) {
             outFilename = filename + ".uncompressed";
         }
         writeFile = File::open(outFilename, 'w').value;
-        writeFile->write(unsigneddata);
+        writeFile->write(decompressed.value);
         writeFile->close();
     } else {
-        std::vector<uint8_t> bytes = file->read(file->size.value).value; // this is what you get from lib/file IIRC
-        std::vector<char> differentBytes = std::vector<char>(bytes.begin(), bytes.end());
+        std::vector<uint8_t> bytes = file->read(file->size.value).value;
 
-        std::vector<char> compressed = compressData(differentBytes.data(), file->size.value);
-        std::vector<unsigned char> unsigneddata = std::vector<unsigned char>(compressed.begin(), compressed.end());
+        ErrorOr<std::vector<uint8_t>> compressed = zlib::compressData(bytes);
+        if (compressed.isError) {
+            std::cout << "Error: Failed to compress: " << filename << std::endl;
+            delete file;
+            // not cleaning up writeFile here bc it hasn't been created
+            return EXIT_RUNTIME;
+        }
         writeFile = File::open(filename + ".zz", 'w').value;
-        writeFile->write(unsigneddata);
+        writeFile->write(compressed.value);
         writeFile->close();
    	}
+
+    delete file;
+    delete writeFile;
 }