diff --git a/aws/rust-runtime/aws-config/Cargo.toml b/aws/rust-runtime/aws-config/Cargo.toml
index d5766bb0da..2577974bbe 100644
--- a/aws/rust-runtime/aws-config/Cargo.toml
+++ b/aws/rust-runtime/aws-config/Cargo.toml
@@ -52,7 +52,7 @@ async-trait = "0.1.51"
 env_logger = "0.9.0"
 
 # used for fuzzing profile parsing
-arbitrary = "1.0.2"
+arbitrary = "=1.1.3" # 1.1.4 requires Rust 1.63 to compile
 
 # used for test case deserialization
 serde = { version = "1", features = ["derive"] }
diff --git a/rust-runtime/aws-smithy-eventstream/Cargo.toml b/rust-runtime/aws-smithy-eventstream/Cargo.toml
index dda95659be..c36cc9713a 100644
--- a/rust-runtime/aws-smithy-eventstream/Cargo.toml
+++ b/rust-runtime/aws-smithy-eventstream/Cargo.toml
@@ -11,7 +11,7 @@ repository = "https://github.com/awslabs/smithy-rs"
 derive-arbitrary = ["arbitrary"]
 
 [dependencies]
-arbitrary = { version = "1", optional = true, features = ["derive"] }
+arbitrary = { version = "=1.1.3", optional = true, features = ["derive"] } # 1.1.4 requires Rust 1.63 to compile
 aws-smithy-types = { path = "../aws-smithy-types" }
 bytes = "1"
 crc32fast = "1.3"
diff --git a/rust-runtime/aws-smithy-eventstream/fuzz/Cargo.toml b/rust-runtime/aws-smithy-eventstream/fuzz/Cargo.toml
index e81cb41f97..d6301e76df 100644
--- a/rust-runtime/aws-smithy-eventstream/fuzz/Cargo.toml
+++ b/rust-runtime/aws-smithy-eventstream/fuzz/Cargo.toml
@@ -9,7 +9,7 @@ edition = "2021"
 cargo-fuzz = true
 
 [dependencies]
-arbitrary = { version = "1", features = ["derive"] }
+arbitrary = { version = "=1.1.3", optional = true, features = ["derive"] } # 1.1.4 requires Rust 1.63 to compile
 aws-smithy-types = { path = "../../aws-smithy-types" }
 bytes = "1"
 crc32fast = "1"