diff --git a/README.md b/README.md
index 788271f..c7a6475 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@ An interactive playground for the Gleam language.
 ```sh
 # Set the gleam version in the GLEAM_VERSION file
 #./GLEAM_VERSION
-v1.11.0
+v1.18.1
 
 # Download a wasm version of the Gleam compiler
 ./bin/download-compiler
diff --git a/test/playground_test.gleam b/test/playground_test.gleam
index 3831e7a..c78ff0d 100644
--- a/test/playground_test.gleam
+++ b/test/playground_test.gleam
@@ -1,12 +1,59 @@
+import gleam/list
+import gleam/string
 import gleeunit
-import gleeunit/should
+import simplifile
 
 pub fn main() {
   gleeunit.main()
 }
 
 // gleeunit test functions end in `_test`
-pub fn hello_world_test() {
-  1
-  |> should.equal(1)
+pub fn gleam_version_matches_compiler_test() {
+  let assert Ok(fingerprint) =
+    simplifile.read("build/dev/javascript/fingerprint")
+  let assert [version, ..] = string.split(fingerprint, " ")
+  let assert Ok(gleam_version) = simplifile.read("GLEAM_VERSION")
+  let assert Ok(deploy_workflow) =
+    simplifile.read(".github/workflows/deploy.yml")
+  let assert Ok(test_workflow) = simplifile.read(".github/workflows/test.yml")
+  let assert Ok(readme) = simplifile.read("README.md")
+
+  assert string.trim(gleam_version) == "v" <> version
+    as "GLEAM_VERSION must match the Gleam compiler version."
+  assert workflow_gleam_version(deploy_workflow) == version
+    as "The deploy workflow must match the Gleam compiler version."
+  assert workflow_gleam_version(test_workflow) == version
+    as "The test workflow must match the Gleam compiler version."
+  assert readme_gleam_version(readme) == version
+    as "The ./GLEAM_VERSION in README must match the Gleam compiler version."
+}
+
+fn workflow_gleam_version(workflow: String) -> String {
+  let version_lines =
+    workflow
+    |> string.split("\n")
+    |> list.filter(fn(line) { string.contains(line, "gleam-version:") })
+
+  case version_lines {
+    [line] ->
+      line
+      |> string.trim
+      |> string.replace("gleam-version: ", "")
+      |> string.replace("\"", "")
+    _ -> ""
+  }
+}
+
+fn readme_gleam_version(readme: String) -> String {
+  case string.split(readme, "#./GLEAM_VERSION\n") {
+    [_, version_and_rest] ->
+      case string.split(version_and_rest, "\n") {
+        [readme_version, ..] ->
+          readme_version
+          |> string.trim
+          |> string.replace("v", "")
+        _ -> ""
+      }
+    _ -> ""
+  }
 }