diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 379ce63..f5159ba 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -18,7 +18,7 @@ jobs:
       matrix:
         name: [Linux]
         os: [ubuntu]
-        rust: [nightly, beta, stable, 1.62.0, 1.0.0, 18 months ago, stable minus 8 releases]
+        rust: [nightly, beta, stable, 1.62.0, 1.0.0, stable 18 months ago, stable minus 8 releases]
         include:
           - name: macOS
             os: macos
@@ -28,7 +28,7 @@ jobs:
             rust: 1.62.0
           - name: macOS
             os: macos
-            rust: 18 months ago
+            rust: stable 18 months ago
           - name: macOS
             os: macos
             rust: stable minus 8 releases
@@ -40,7 +40,7 @@ jobs:
             rust: 1.62.0
           - name: Windows
             os: windows
-            rust: 18 months ago
+            rust: stable 18 months ago
           - name: Windows
             os: windows
             rust: stable minus 8 releases
diff --git a/README.md b/README.md
index a04a49b..6ec4744 100644
--- a/README.md
+++ b/README.md
@@ -67,7 +67,7 @@ compiler support.
      # offset, which may be written in years, months, weeks, or days.
   - uses: dtolnay/rust-toolchain@master
     with:
-      toolchain: 18 months ago
+      toolchain: stable 18 months ago
 ```
 
 ```yaml
diff --git a/action.yml b/action.yml
index cc7f9cc..aa1928a 100644
--- a/action.yml
+++ b/action.yml
@@ -30,11 +30,11 @@ runs:
     - id: parse
       run: |
         : parse toolchain version
-        if [[ $toolchain =~ ^[0-9]+' '(year|month|week|day)s?' 'ago$ ]]; then
+        if [[ $toolchain =~ ^stable' '[0-9]+' '(year|month|week|day)s?' 'ago$ ]]; then
           if [[ ${{runner.os}} == macOS ]]; then
-            echo "::set-output name=toolchain::1.$((($(date -v-$(sed 's/\([0-9]*\) \(.\).*/\1\2/' <<< $toolchain) +%s)/60/60/24-16569)/7/6))"
+            echo "::set-output name=toolchain::1.$((($(date -v-$(sed 's/stable \([0-9]*\) \(.\).*/\1\2/' <<< $toolchain) +%s)/60/60/24-16569)/7/6))"
           else
-            echo "::set-output name=toolchain::1.$((($(date --date "$toolchain" +%s)/60/60/24-16569)/7/6))"
+            echo "::set-output name=toolchain::1.$((($(date --date "${toolchain#stable }" +%s)/60/60/24-16569)/7/6))"
           fi
         elif [[ $toolchain =~ ^stable' 'minus' '[0-9]+' 'releases?$ ]]; then
           echo "::set-output name=toolchain::1.$((($(date +%s)/60/60/24-16569)/7/6-${toolchain//[^0-9]/}))"