diff --git a/02_quickstart_aggregation/Cargo.lock b/02_quickstart_aggregation/Cargo.lock
index d9e048f..246d388 100644
--- a/02_quickstart_aggregation/Cargo.lock
+++ b/02_quickstart_aggregation/Cargo.lock
@@ -1,5 +1,7 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+version = 3
+
 [[package]]
 name = "async-trait"
 version = "0.1.30"
@@ -379,7 +381,7 @@ dependencies = [
  "http",
  "indexmap",
  "slab",
- "tokio",
+ "tokio 0.2.25",
  "tokio-util",
  "tracing",
  "tracing-futures",
@@ -481,7 +483,7 @@ dependencies = [
  "itoa",
  "pin-project",
  "socket2",
- "tokio",
+ "tokio 0.2.25",
  "tower-service",
  "tracing",
  "want",
@@ -498,7 +500,7 @@ dependencies = [
  "hyper",
  "log",
  "rustls",
- "tokio",
+ "tokio 0.2.25",
  "tokio-rustls",
  "webpki",
 ]
@@ -652,9 +654,9 @@ dependencies = [
 
 [[package]]
 name = "mio"
-version = "0.6.21"
+version = "0.6.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "302dec22bcf6bae6dfb69c647187f4b4d0fb6f535521f7bc022430ce8e12008f"
+checksum = "4afd66f5b91bf2a3bc13fad0e21caedac168ca4c707504e75585648ae80e4cc4"
 dependencies = [
  "cfg-if 0.1.10",
  "fuchsia-zircon",
@@ -671,9 +673,9 @@ dependencies = [
 
 [[package]]
 name = "miow"
-version = "0.2.1"
+version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8c1f2f3b1cf331de6896aabf6e9d55dca90356cc9960cca7eaaf408a355ae919"
+checksum = "ebd808424166322d4a38da87083bfddd3ac4c131334ed55856112eb06d46944d"
 dependencies = [
  "kernel32-sys",
  "net2",
@@ -715,7 +717,7 @@ dependencies = [
  "strsim",
  "take_mut",
  "time",
- "tokio",
+ "tokio 0.2.25",
  "tokio-rustls",
  "trust-dns-proto",
  "trust-dns-resolver",
@@ -728,9 +730,9 @@ dependencies = [
 
 [[package]]
 name = "net2"
-version = "0.2.33"
+version = "0.2.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "42550d9fb7b6684a6d404d9fa7250c2eb2646df731d1c06afc06dcee9e1bcf88"
+checksum = "391630d12b68002ae1e25e8f974306474966550ad82dac6886fb8910c19568ae"
 dependencies = [
  "cfg-if 0.1.10",
  "libc",
@@ -987,7 +989,7 @@ dependencies = [
  "serde",
  "serde_json",
  "serde_urlencoded",
- "tokio",
+ "tokio 0.2.25",
  "tokio-rustls",
  "url",
  "wasm-bindgen",
@@ -1030,7 +1032,7 @@ dependencies = [
  "mongodb",
  "serde",
  "serde_json",
- "tokio",
+ "tokio 1.8.4",
 ]
 
 [[package]]
@@ -1301,9 +1303,9 @@ dependencies = [
 
 [[package]]
 name = "tokio"
-version = "0.2.19"
+version = "0.2.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7d9c43f1bb96970e153bcbae39a65e249ccb942bd9d36dbdf086024920417c9c"
+checksum = "6703a273949a90131b290be1fe7b039d0fc884aa1935860dfcbe056f28cd8092"
 dependencies = [
  "bytes 0.5.4",
  "fnv",
@@ -1318,11 +1320,21 @@ dependencies = [
  "tokio-macros",
 ]
 
+[[package]]
+name = "tokio"
+version = "1.8.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "50dae83881bc9b0403dd5b44ea9deed3e939856cc8722d5be37f0d6e5c6d53dd"
+dependencies = [
+ "autocfg",
+ "pin-project-lite 0.2.6",
+]
+
 [[package]]
 name = "tokio-macros"
-version = "0.2.5"
+version = "0.2.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f0c3acc6aa564495a0f2e1d59fab677cd7f81a19994cfc7f3ad0e64301560389"
+checksum = "e44da00bfc73a25f814cd8d7e57a68a5c31b74b3152a0a1d1f590c97ed06265a"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1337,7 +1349,7 @@ checksum = "4adb8b3e5f86b707f1b54e7c15b6de52617a823608ccda98a15d3a24222f265a"
 dependencies = [
  "futures-core",
  "rustls",
- "tokio",
+ "tokio 0.2.25",
  "webpki",
 ]
 
@@ -1352,7 +1364,7 @@ dependencies = [
  "futures-sink",
  "log",
  "pin-project-lite 0.1.4",
- "tokio",
+ "tokio 0.2.25",
 ]
 
 [[package]]
@@ -1409,7 +1421,7 @@ dependencies = [
  "rand",
  "smallvec",
  "thiserror",
- "tokio",
+ "tokio 0.2.25",
  "url",
 ]
 
@@ -1428,7 +1440,7 @@ dependencies = [
  "resolv-conf",
  "smallvec",
  "thiserror",
- "tokio",
+ "tokio 0.2.25",
  "trust-dns-proto",
 ]
 
diff --git a/02_quickstart_aggregation/Cargo.toml b/02_quickstart_aggregation/Cargo.toml
index 45c62be..c407e75 100644
--- a/02_quickstart_aggregation/Cargo.toml
+++ b/02_quickstart_aggregation/Cargo.toml
@@ -6,7 +6,7 @@ edition = "2018"
 
 [dependencies]
 mongodb = { version = "1.2.0" }
-tokio = "0.2.19"
+tokio = "1.8.4"
 chrono = "0.4.11"
 serde = "1.0.105"
 serde_json = "1.0.53"