diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index ef16589a..a8d13822 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -20,16 +20,16 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-13, macos-latest ] #, windows-latest]
+        os: [ubuntu-latest, macos-15-intel, macos-latest ] #, windows-latest]
         python-version: ["3.13"]  # ["2.7", "3.7", "3.8", "3.9", "3.10", "3.11", "3.12", "pypy3"]
 
         include:
           # By default, specify an OSX_VER of 11.0, triggering ARM64 build.
           - python-osx-ver: "11.0"
 
-          # macos-13 is the last remaining x86-64 runner;
+          # macos-15-intel is the last remaining x86-64 runner;
           # set OSX_VER to 10.9 trigger x86_64 builds by default.
-          - os: macos-13
+          - os: macos-15-intel
             python-osx-ver: "10.9"
 
     # The type of runner that the job will run on
diff --git a/library_builders.sh b/library_builders.sh
index 7f41a727..685a05e6 100644
--- a/library_builders.sh
+++ b/library_builders.sh
@@ -12,8 +12,8 @@ OPENBLAS_LIB_URL="https://anaconda.org/multibuild-wheels-staging/openblas-libs"
 # Recipes for building some libraries
 OPENBLAS_VERSION="${OPENBLAS_VERSION:-0.3.10}"
 # We use system zlib by default - see build_new_zlib
-ZLIB_VERSION="${ZLIB_VERSION:-1.2.10}"
-LIBPNG_VERSION="${LIBPNG_VERSION:-1.6.37}"
+ZLIB_VERSION="${ZLIB_VERSION:-1.3.1}"
+LIBPNG_VERSION="${LIBPNG_VERSION:-1.6.50}"
 BZIP2_VERSION="${BZIP2_VERSION:-1.0.7}"
 FREETYPE_VERSION="${FREETYPE_VERSION:-2.11.0}"
 TIFF_VERSION="${TIFF_VERSION:-4.1.0}"