diff --git a/pkgs/development/tools/fable/default.nix b/pkgs/development/tools/fable/default.nix
index cf05403e0256..93757b3cd8e2 100644
--- a/pkgs/development/tools/fable/default.nix
+++ b/pkgs/development/tools/fable/default.nix
@@ -2,9 +2,10 @@
 
 buildDotnetGlobalTool {
   pname = "fable";
-  version = "4.5.0";
+  version = "4.9.0";
 
-  nugetSha256 = "sha256-KeNkS2fuZFnI8WVqSpIRjo2eA+XKuHLLpMIzDzgqXdg=";
+  nugetSha256 = "sha256-BB3jCsIz6Y9LjBhoEBzYLXttwLOBb4n1EpqJwImjo9A=";
+  passthru.updateScript = ./update.sh;
 
   meta = with lib; {
     description = "Fable is an F# to JavaScript compiler";
diff --git a/pkgs/development/tools/fable/update.sh b/pkgs/development/tools/fable/update.sh
new file mode 100755
index 000000000000..9d23084ebd85
--- /dev/null
+++ b/pkgs/development/tools/fable/update.sh
@@ -0,0 +1,39 @@
+#!/usr/bin/env nix-shell
+#!nix-shell -i bash -p curl gnused nix-prefetch jq
+
+set -euo pipefail
+URL="https://github.com/fable-compiler/fable"
+PKG="Fable"
+ROOT="$(dirname "$(readlink -f "$0")")"
+NIX_DRV="$ROOT/default.nix"
+if [ ! -f "$NIX_DRV" ]; then
+  echo "ERROR: cannot find default.nix in $ROOT"
+  exit 1
+fi
+
+TMP="$(mktemp -d)"
+clean_up() {
+    rm -rf "$TMP"
+}
+trap clean_up EXIT SIGINT SIGTERM
+PACKAGES="$TMP/packages"
+SRC_RW="$TMP/src"
+
+mkdir -p $SRC_RW
+mkdir -p $PACKAGES
+
+
+VER=$(curl -s "https://api.github.com/repos/fable-compiler/fable/releases/latest" | jq -r .tag_name | grep -oP '\d+\.\d+\.\d+' )
+
+CURRENT_VER=$(grep -oP '(?<=version = ")[^"]+' "$NIX_DRV")
+if [[ "$CURRENT_VER" == "$VER" ]]; then
+    echo "$PKG is already up to date: $CURRENT_VER"
+    exit
+fi
+
+
+NUGET_URL="$(curl -f "https://api.nuget.org/v3/index.json" | jq --raw-output '.resources[] | select(."@type" == "PackageBaseAddress/3.0.0")."@id"')$PKG/$VER/$PKG.$VER.nupkg"
+HASH=$(nix-hash --to-sri --type sha256 "$(nix-prefetch-url "$NUGET_URL")")
+
+sed -i "s/version = \".*\"/version = \"$VER\"/" "$NIX_DRV"
+sed -i "s#nugetSha256 = \"sha256-.\{44\}\"#nugetSha256 = \"$HASH\"#" "$NIX_DRV"