diff --git a/.circleci/config.yml b/.circleci/config.yml
index bd19cd6..1a0c76f 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -14,7 +14,7 @@ workflows:
                 # be easier on the CI hosts since presumably those fat lower layers will already be cached, and
                 # therefore faster than a minimal, customized alpine.
                 # MSRV
-                'rust:1.47.0'
+                'rust:1.51.0'
               ]
               # a hacky scheme to work around CircleCI's inability to deal with mutable docker tags, forcing us to
               # get a nightly or stable toolchain via rustup instead of a mutable docker tag
diff --git a/Cargo.toml b/Cargo.toml
index bd601ea..9592b7c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,7 +10,7 @@ keywords = ["base64", "utf8", "encode", "decode", "no_std"]
 categories = ["encoding"]
 license = "MIT OR Apache-2.0"
 edition = "2018"
-rust-version = "1.47.0"
+rust-version = "1.51.0"
 
 [[bench]]
 name = "benchmarks"
diff --git a/README.md b/README.md
index 2b87943..f48a201 100644
--- a/README.md
+++ b/README.md
@@ -45,7 +45,7 @@ If you have a `Read` (e.g. reading a file or network socket), there are various
 
 ## Rust version compatibility
 
-The minimum required Rust version is 1.47.0.
+The minimum required Rust version is 1.51.0.
 
 # Contributing
 
diff --git a/RELEASE-NOTES.md b/RELEASE-NOTES.md
index 7b11df9..eaf84dc 100644
--- a/RELEASE-NOTES.md
+++ b/RELEASE-NOTES.md
@@ -1,5 +1,9 @@
 # 0.20.0
 
+## Next
+
+- MSRV is now 1.51.0 to keep up with `criterion`
+
 ## 0.20.0-alpha.1
 
 ### Breaking changes
@@ -13,6 +17,10 @@
 - `DecoderReader` now owns its inner reader, and can expose it via `into_inner()`. For symmetry, `EncoderWriter` can do the same with its writer.
 - `encoded_len` is now public so you can size encode buffers precisely.
 
+# 0.13.1
+
+- More precise decode buffer sizing, avoiding unnecessary allocation in `decode_config`.
+
 # 0.13.0
 
 - Config methods are const
diff --git a/clippy.toml b/clippy.toml
index dbabdab..434e968 100644
--- a/clippy.toml
+++ b/clippy.toml
@@ -1 +1 @@
-msrv = "1.47.0"
+msrv = "1.51.0"
diff --git a/src/decode.rs b/src/decode.rs
index d7b4195..04db879 100644
--- a/src/decode.rs
+++ b/src/decode.rs
@@ -95,7 +95,14 @@ pub fn decode_engine<E: Engine, T: AsRef<[u8]>>(
     input: T,
     engine: &E,
 ) -> Result<Vec<u8>, DecodeError> {
-    let mut buffer = Vec::<u8>::new();
+    let decoded_length_estimate = (input
+        .as_ref()
+        .len()
+        .checked_add(3)
+        .expect("decoded length calculation overflow"))
+        / 4
+        * 3;
+    let mut buffer = Vec::<u8>::with_capacity(decoded_length_estimate);
     decode_engine_vec(input, &mut buffer, engine).map(|_| buffer)
 }
 
@@ -340,4 +347,17 @@ mod tests {
             assert_eq!(orig_data, decode_buf);
         }
     }
+
+    #[test]
+    fn decode_engine_estimation_works_for_various_lengths() {
+        for num_prefix_quads in 0..100 {
+            for suffix in &["AA", "AAA", "AAAA"] {
+                let mut prefix = "AAAA".repeat(num_prefix_quads);
+                prefix.push_str(suffix);
+                // make sure no overflow (and thus a panic) occurs
+                let res = decode_engine(prefix, &DEFAULT_ENGINE);
+                assert!(res.is_ok());
+            }
+        }
+    }
 }