diff --git a/.github/workflows/full_ci.yml b/.github/workflows/full_ci.yml
index 404e0f3bf092..13f26ac6fa2d 100644
--- a/.github/workflows/full_ci.yml
+++ b/.github/workflows/full_ci.yml
@@ -154,7 +154,7 @@ jobs:
           stable,
           beta,
           nightly,
-          1.71.0,
+          1.63.0,
         ]
     steps:
       - uses: actions/checkout@v4
@@ -179,7 +179,7 @@ jobs:
           - { toolchain: stable, os: macos-14 }
           - { toolchain: beta, os: macos-14 }
           - { toolchain: nightly, os: macos-14 }
-          - { toolchain: 1.71.0, os: macos-14 }
+          - { toolchain: 1.63.0, os: macos-14 }
     runs-on: ${{ matrix.target.os }}
     steps:
       - uses: actions/checkout@v4
@@ -200,7 +200,7 @@ jobs:
       fail-fast: true
       matrix:
         toolchain: [
-          1.71.0,
+          1.63.0,
           stable,
         ]
     steps:
diff --git a/Cargo.toml b/Cargo.toml
index 11b54fa0b344..ffce4f3241bd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -14,7 +14,7 @@ exclude = ["/ci/*", "/.github/*", "/.cirrus.yml", "/triagebot.toml"]
 description = """
 Raw FFI bindings to platform libraries like libc.
 """
-rust-version = "1.71.0"
+rust-version = "1.63.0"
 
 [package.metadata.docs.rs]
 features = ["const-extern-fn", "extra_traits"]
diff --git a/README.md b/README.md
index 2ba6b9ced923..da5a64f2e108 100644
--- a/README.md
+++ b/README.md
@@ -52,7 +52,7 @@ libc = "0.2"
 
 ## Rust version support
 
-The minimum supported Rust toolchain version is currently **Rust 1.71.0**
+The minimum supported Rust toolchain version is currently **Rust 1.63.0**
 (libc does not currently have any policy regarding changes to the minimum
 supported Rust version; such policy is a work in progress).