diff --git a/Cargo.lock b/Cargo.lock
index 46f0b9a41..054a5a3a4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1250,9 +1250,9 @@ dependencies = [
 
 [[package]]
 name = "flate2"
-version = "1.0.20"
+version = "1.0.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cd3aec53de10fe96d7d8c565eb17f2c687bb5518a2ec453b5b1252964526abe0"
+checksum = "80edafed416a46fb378521624fab1cfa2eb514784fd8921adbe8a8d8321da811"
 dependencies = [
  "cfg-if 1.0.0",
  "crc32fast",
diff --git a/core/Cargo.toml b/core/Cargo.toml
index 9350748a8..f995d61b3 100644
--- a/core/Cargo.toml
+++ b/core/Cargo.toml
@@ -8,7 +8,7 @@ license = "MIT OR Apache-2.0"
 [dependencies]
 byteorder = "1.4"
 bitstream-io = "1.2.0"
-flate2 = "1.0.20"
+flate2 = "1.0.21"
 fnv = "1.0.7"
 gc-arena = { git = "https://github.com/ruffle-rs/gc-arena" }
 gc-arena-derive = { git = "https://github.com/ruffle-rs/gc-arena" }