diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index fcf73b5d58..37d8670553 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -40,6 +40,7 @@ jobs:
       CCACHE_BASEDIR: ${{ github.workspace }}
       CCACHE_DIR: ${{ github.workspace }}/.ccache
       CCACHE_MAXSIZE: 500M
+      DOWNLOAD_CACHE: ${{ github.workspace }}/.ccache/downloads
       TARGET: ${{ matrix.arch }}-w64-mingw32
       RUST_TARGET: ${{ matrix.arch }}-pc-windows-gnu
     strategy:
diff --git a/ci/build-mingw64.sh b/ci/build-mingw64.sh
index 1687de287b..9139b3955c 100755
--- a/ci/build-mingw64.sh
+++ b/ci/build-mingw64.sh
@@ -108,12 +108,23 @@ function gettar {
     local dname="$2"
     [ -z "$dname" ] && dname="${fname%.tar.*}"
     [ -d "$dname" ] && return 0
-    $wget "$1" -O "$fname"
+    local cachename="$(md5sum <<<"$1" | cut -d " " -f 1)"
+    if [[ -n "$DOWNLOAD_CACHE" && -s "$DOWNLOAD_CACHE/$cachename" ]]; then
+        cp -v "$DOWNLOAD_CACHE/$cachename" "$fname"
+        cachename=
+    else
+        $wget "$1" -O "$fname"
+    fi
     tar -xaf "$fname"
     if [ ! -d "$dname" ]; then
         echo "Error: expected $fname to extract to $dname but it was not created" >&2
         return 2
     fi
+    if [[ -n "$DOWNLOAD_CACHE" && -n "$cachename" ]]; then
+        # assume successful extraction means the file was fine
+        mkdir -p "$DOWNLOAD_CACHE"
+        cp -v "$fname" "$DOWNLOAD_CACHE/$cachename"
+    fi
 }
 
 function build_if_missing {