diff --git a/install_libpng_wasi.sh b/install_libpng_wasi.sh
index b167378..0e3d642 100755
--- a/install_libpng_wasi.sh
+++ b/install_libpng_wasi.sh
@@ -27,7 +27,9 @@ if [ -f "$ZLIB_TARBALL" ]; then
     echo "Tarball $ZLIB_TARBALL already exists. Skipping re-download."
 else
     echo "Tarball $ZLIB_TARBALL does not exist. Downloading the tarball."
-    wget https://zlib.net/$ZLIB.tar.gz
+    # zlib.net only serves the current release at the root; older versions are
+    # permanently archived under /fossils/. (Was https://zlib.net/$ZLIB.tar.gz, now 404.)
+    wget https://zlib.net/fossils/$ZLIB.tar.gz
 fi
 
 # Check if the directory already exists