diff --git a/.github/workflows/ci_test.yml b/.github/workflows/ci_test.yml
index 36d56b4..14f2bcf 100644
--- a/.github/workflows/ci_test.yml
+++ b/.github/workflows/ci_test.yml
@@ -57,7 +57,7 @@ jobs:
     strategy:
       matrix:
         os: [ ubuntu-latest, windows-latest, macos-latest ]
-        rust: [ stable, 1.60.0 ]
+        rust: [ stable, 1.64.0 ]
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v2
diff --git a/README.md b/README.md
index 0191a38..810a7a2 100644
--- a/README.md
+++ b/README.md
@@ -60,7 +60,8 @@ See
 
 ## Minimal rust version
 
-The earliest supported rust version is currently "1.60.0".
+The minimal supported rust version is currently "1.64.0",
+due to a change in a patch version of a dependency.
 
 ## Crate Features