diff --git a/libs/compress/picompress.cpp b/libs/compress/picompress.cpp
index 90e915e9..b52eaa3d 100644
--- a/libs/compress/picompress.cpp
+++ b/libs/compress/picompress.cpp
@@ -68,7 +68,7 @@ PIByteArray piDecompress(const PIByteArray & zba) {
 	ba.resize(sz);
 	int ret = 0;
 	ulong s = sz;
-	ret     = uncompress(ba.data(), &s, zba.data(), zba.size());
+	ret     = uncompress(ba.data(), &s, zba.data(), zba.size() - sizeof(ullong));
 	if (ret != Z_OK) {
 		piCout << "[PICompress]"
 			   << "Error: invalid input or not enought memory"_tr("PICompress");