diff --git a/dist/setup.js b/dist/setup.js
index 1ee3601..af16e2b 100644
--- a/dist/setup.js
+++ b/dist/setup.js
@@ -11,6 +11,11 @@ export default async () => {
     if (process.platform === "win32") {
         throw new Error("Flox is not supported on Windows");
     }
+    // verify that nix is installed
+    const { exitCode } = await getExecOutput("nix", ["--version"]);
+    if (exitCode !== 0) {
+        throw new Error("Nix is not installed, please install it first, see https://github.com/DeterminateSystems/nix-installer-action");
+    }
     const cacheKey = `floxcache-${process.platform}-${process.arch}`;
     const cacheEnabled = cache.isFeatureAvailable();
     let cacheHit = false;
diff --git a/src/setup.ts b/src/setup.ts
index 5f6d438..4c7599d 100644
--- a/src/setup.ts
+++ b/src/setup.ts
@@ -16,6 +16,13 @@ export default async (): Promise<{
   if (process.platform === "win32") {
     throw new Error("Flox is not supported on Windows");
   }
+  // verify that nix is installed
+  const { exitCode } = await getExecOutput("nix", ["--version"]);
+  if (exitCode !== 0) {
+    throw new Error(
+      "Nix is not installed, please install it first, see https://github.com/DeterminateSystems/nix-installer-action"
+    );
+  }
   const cacheKey = `floxcache-${process.platform}-${process.arch}`;
   const cacheEnabled = cache.isFeatureAvailable();
   let cacheHit = false;