diff --git a/Cargo.lock b/Cargo.lock
index f794b7dd..c432ad7a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2982,9 +2982,9 @@ dependencies = [
 
 [[package]]
 name = "once_cell"
-version = "1.14.0"
+version = "1.15.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2f7254b99e31cad77da24b08ebf628882739a608578bb1bcdfc1f9c21260d7c0"
+checksum = "e82dad04139b71a90c080c8463fe0dc7902db5192d939bd0950f074d014339e1"
 
 [[package]]
 name = "oorandom"
diff --git a/zebra-consensus/Cargo.toml b/zebra-consensus/Cargo.toml
index 999e0a19..03c8ee00 100644
--- a/zebra-consensus/Cargo.toml
+++ b/zebra-consensus/Cargo.toml
@@ -22,7 +22,7 @@ chrono = { version = "0.4.22", default-features = false, features = ["clock", "s
 dirs = "4.0.0"
 displaydoc = "0.2.3"
 lazy_static = "1.4.0"
-once_cell = "1.14.0"
+once_cell = "1.15.0"
 serde = { version = "1.0.144", features = ["serde_derive"] }
 
 futures = "0.3.24"
diff --git a/zebra-state/Cargo.toml b/zebra-state/Cargo.toml
index 96465e4b..f58e36da 100644
--- a/zebra-state/Cargo.toml
+++ b/zebra-state/Cargo.toml
@@ -43,7 +43,7 @@ color-eyre = "0.6.1"
 # Enable a feature that makes tinyvec compile much faster.
 tinyvec = { version = "1.6.0", features = ["rustc_1_55"] }
 
-once_cell = "1.14.0"
+once_cell = "1.15.0"
 spandoc = "0.2.2"
 
 hex = { version = "0.4.3", features = ["serde"] }
diff --git a/zebra-test/Cargo.toml b/zebra-test/Cargo.toml
index cf2db1c4..5448aa88 100644
--- a/zebra-test/Cargo.toml
+++ b/zebra-test/Cargo.toml
@@ -13,7 +13,7 @@ indexmap = "1.9.1"
 lazy_static = "1.4.0"
 insta = "1.20.0"
 proptest = "0.10.1"
-once_cell = "1.14.0"
+once_cell = "1.15.0"
 rand = { version = "0.8.5", package = "rand" }
 regex = "1.6.0"
 
diff --git a/zebrad/Cargo.toml b/zebrad/Cargo.toml
index ef2bdbfc..c7732838 100644
--- a/zebrad/Cargo.toml
+++ b/zebrad/Cargo.toml
@@ -151,7 +151,7 @@ tonic-build = { version = "0.8.0", optional = true }
 [dev-dependencies]
 abscissa_core = { version = "0.5", features = ["testing"] }
 hex = "0.4.3"
-once_cell = "1.14.0"
+once_cell = "1.15.0"
 regex = "1.6.0"
 semver = "1.0.14"