diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6fb9264c21..75b09963ec 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -191,7 +191,7 @@ jobs:
         set -eo pipefail
         # Override the exising `syn` dependency with one which requires an exact
         # version.
-        cargo add -p zerocopy-derive 'syn@=2.0.46'
+        cargo add -p zerocopy-derive 'syn@=2.0.79'
 
     - name: Configure environment variables
       run: |
@@ -613,7 +613,7 @@ jobs:
           #
           # TODO(#1595): Debug why this step is still necessary after #1564 and
           # maybe remove it.
-          cargo add -p zerocopy-derive 'syn@=2.0.46' &> /dev/null
+          cargo add -p zerocopy-derive 'syn@=2.0.79' &> /dev/null
 
           cargo check --workspace --tests            &> /dev/null &
           cargo metadata                             &> /dev/null &
diff --git a/Cargo.toml b/Cargo.toml
index aa0ca6aa77..9d917d4c3b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -71,16 +71,16 @@ zerocopy-derive = { version = "=0.9.0-alpha.0", path = "zerocopy-derive", option
 zerocopy-derive = { version = "=0.9.0-alpha.0", path = "zerocopy-derive" }
 
 [dev-dependencies]
-itertools = "0.11"
+itertools = "0.13.0"
 rand = { version = "0.8.5", default-features = false, features = ["small_rng"] }
-rustversion = "1.0"
-static_assertions = "1.1"
+rustversion = "1.0.17"
+static_assertions = "1.1.0"
 testutil = { path = "testutil" }
 # Pinned to a specific version so that the version used for local development
 # and the version used in CI are guaranteed to be the same. Future versions
 # sometimes change the output format slightly, so a version mismatch can cause
 # CI test failures.
-trybuild = { version = "=1.0.89", features = ["diff"] }
+trybuild = { version = "=1.0.90", features = ["diff"] }
 # In tests, unlike in production, zerocopy-derive is not optional
 zerocopy-derive = { version = "=0.9.0-alpha.0", path = "zerocopy-derive" }
 # TODO(#381) Remove this dependency once we have our own layout gadgets.
diff --git a/zerocopy-derive/Cargo.toml b/zerocopy-derive/Cargo.toml
index 75f345aaa1..d348ef482e 100644
--- a/zerocopy-derive/Cargo.toml
+++ b/zerocopy-derive/Cargo.toml
@@ -32,23 +32,17 @@ proc-macro = true
 [dependencies]
 proc-macro2 = "1.0.1"
 quote = "1.0.10"
-syn = { version = "2.0.46", features = ["full"] }
+syn = { version = "2.0.79", features = ["full"] }
 
 [dev-dependencies]
 dissimilar = "1.0.9"
-# We don't use this directly, but trybuild does. On the MSRV toolchain, the
-# version resolver fails to select any version for once_cell unless we
-# depend on it directly.
-once_cell = "=1.9"
-# This is the latest version which is compatible with `syn` 2.0.46, which we pin
-# to in CI for MSRV compatibility reasons.
-prettyplease = "=0.2.17"
-rustversion = "1.0"
-static_assertions = "1.1"
+prettyplease = "0.2.22"
+rustversion = "1.0.17"
+static_assertions = "1.1.0"
 testutil = { path = "../testutil" }
 # Pinned to a specific version so that the version used for local development
 # and the version used in CI are guaranteed to be the same. Future versions
 # sometimes change the output format slightly, so a version mismatch can cause
 # CI test failures.
-trybuild = { version = "=1.0.89", features = ["diff"] }
+trybuild = { version = "=1.0.90", features = ["diff"] }
 zerocopy = { path = "../", features = ["derive"] }