diff --git a/dist/index.js b/dist/index.js
index 9f6fbdb..61dafb8 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -35718,10 +35718,10 @@ async function run(inputs) {
         await core.group(`Preparing ghcup environment`, async () => {
             // Andreas Abel, 2026-01-01, https://github.com/haskell-actions/setup/issues/78
             // Add ghcup vanilla and prereleases channels by default.
-            (0, installer_1.addGhcupReleaseChannel)('vanilla', os, arch);
-            (0, installer_1.addGhcupReleaseChannel)('prereleases', os, arch);
+            await (0, installer_1.addGhcupReleaseChannel)('vanilla', os, arch);
+            await (0, installer_1.addGhcupReleaseChannel)('prereleases', os, arch);
             if (opts.ghcup.releaseChannel)
-                (0, installer_1.addGhcupReleaseChannel)(opts.ghcup.releaseChannel.toString(), os, arch);
+                await (0, installer_1.addGhcupReleaseChannel)(opts.ghcup.releaseChannel.toString(), os, arch);
         });
         for (const [t, { resolved }] of Object.entries(opts).filter(o => o[1].enable)) {
             await core.group(`Preparing ${t} environment`, async () => (0, installer_1.resetTool)(t, resolved, os, arch));
diff --git a/lib/setup-haskell.js b/lib/setup-haskell.js
index 432afb6..ce6318f 100644
--- a/lib/setup-haskell.js
+++ b/lib/setup-haskell.js
@@ -76,10 +76,10 @@ async function run(inputs) {
         await core.group(`Preparing ghcup environment`, async () => {
             // Andreas Abel, 2026-01-01, https://github.com/haskell-actions/setup/issues/78
             // Add ghcup vanilla and prereleases channels by default.
-            (0, installer_1.addGhcupReleaseChannel)('vanilla', os, arch);
-            (0, installer_1.addGhcupReleaseChannel)('prereleases', os, arch);
+            await (0, installer_1.addGhcupReleaseChannel)('vanilla', os, arch);
+            await (0, installer_1.addGhcupReleaseChannel)('prereleases', os, arch);
             if (opts.ghcup.releaseChannel)
-                (0, installer_1.addGhcupReleaseChannel)(opts.ghcup.releaseChannel.toString(), os, arch);
+                await (0, installer_1.addGhcupReleaseChannel)(opts.ghcup.releaseChannel.toString(), os, arch);
         });
         for (const [t, { resolved }] of Object.entries(opts).filter(o => o[1].enable)) {
             await core.group(`Preparing ${t} environment`, async () => (0, installer_1.resetTool)(t, resolved, os, arch));
diff --git a/src/setup-haskell.ts b/src/setup-haskell.ts
index 30559d1..734efbc 100644
--- a/src/setup-haskell.ts
+++ b/src/setup-haskell.ts
@@ -43,10 +43,14 @@ export default async function run(
     await core.group(`Preparing ghcup environment`, async () => {
       // Andreas Abel, 2026-01-01, https://github.com/haskell-actions/setup/issues/78
       // Add ghcup vanilla and prereleases channels by default.
-      addGhcupReleaseChannel('vanilla', os, arch);
-      addGhcupReleaseChannel('prereleases', os, arch);
+      await addGhcupReleaseChannel('vanilla', os, arch);
+      await addGhcupReleaseChannel('prereleases', os, arch);
       if (opts.ghcup.releaseChannel)
-        addGhcupReleaseChannel(opts.ghcup.releaseChannel.toString(), os, arch);
+        await addGhcupReleaseChannel(
+          opts.ghcup.releaseChannel.toString(),
+          os,
+          arch
+        );
     });
 
     for (const [t, {resolved}] of Object.entries(opts).filter(