diff --git a/Cargo.lock b/Cargo.lock
index 163e4d9..3c72a1f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -456,7 +456,7 @@ version = "0.1.0"
 dependencies = [
  "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "hex 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "proptest 0.9.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proptest 0.9.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "ring 0.13.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -1156,7 +1156,7 @@ dependencies = [
 
 [[package]]
 name = "proptest"
-version = "0.9.3"
+version = "0.9.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "bit-set 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2301,7 +2301,7 @@ dependencies = [
 "checksum pkg-config 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)" = "676e8eb2b1b4c9043511a9b7bea0915320d7e502b0a079fb03f9635a5252b18c"
 "checksum pretty_env_logger 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "df8b3f4e0475def7d9c2e5de8e5a1306949849761e107b360d03e98eafaffd61"
 "checksum proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)" = "cf3d2011ab5c909338f7887f4fc896d35932e29146c12c8d01da6b22a80ba759"
-"checksum proptest 0.9.3 (registry+https://github.com/rust-lang/crates.io-index)" = "2afed8cbdc8a64b58a5c021757a782351ec1afee85be374872721c84d5da5d80"
+"checksum proptest 0.9.4 (registry+https://github.com/rust-lang/crates.io-index)" = "cf147e022eacf0c8a054ab864914a7602618adba841d800a9a9868a5237a529f"
 "checksum publicsuffix 1.5.2 (registry+https://github.com/rust-lang/crates.io-index)" = "5afecba86dcf1e4fd610246f89899d1924fe12e1e89f555eb7c7f710f3c5ad1d"
 "checksum quick-error 1.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "9274b940887ce9addde99c4eee6b5c44cc494b182b97e73dc8ffdcb3397fd3f0"
 "checksum quote 0.6.12 (registry+https://github.com/rust-lang/crates.io-index)" = "faf4799c5d274f3868a4aae320a0a182cbd2baee377b378f080e16a23e9d80db"
diff --git a/crypto/Cargo.toml b/crypto/Cargo.toml
index 06ee6e0..0e1b9e8 100644
--- a/crypto/Cargo.toml
+++ b/crypto/Cargo.toml
@@ -10,4 +10,4 @@ hex = "0.3.2"
 ring = "0.13.5"
 
 [dev-dependencies]
-proptest = "0.9.3"
+proptest = "0.9.4"