diff --git a/metrics-exporter-tcp/Cargo.toml b/metrics-exporter-tcp/Cargo.toml
index 45105e6c..ccd00a48 100644
--- a/metrics-exporter-tcp/Cargo.toml
+++ b/metrics-exporter-tcp/Cargo.toml
@@ -20,13 +20,13 @@ keywords = ["metrics", "telemetry", "tcp"]
 metrics = { version = "^0.21", path = "../metrics" }
 bytes = { version = "1", default-features = false }
 crossbeam-channel = { version = "0.5", default-features = false, features = ["std"] }
-prost = { version = "0.11", default-features = false }
-prost-types = { version = "0.11", default-features = false, features = ["std"] }
+prost = { version = "0.12", default-features = false }
+prost-types = { version = "0.12", default-features = false, features = ["std"] }
 mio = { version = "0.8", default-features = false, features = ["os-poll", "net"] }
 tracing = { version = "0.1", default-features = false, features = ["attributes"] }
 
 [build-dependencies]
-prost-build = "0.11"
+prost-build = "0.12"
 home = "=0.5.5"
 
 [dev-dependencies]
diff --git a/metrics-observer/Cargo.toml b/metrics-observer/Cargo.toml
index 6dad4911..17594281 100644
--- a/metrics-observer/Cargo.toml
+++ b/metrics-observer/Cargo.toml
@@ -21,12 +21,12 @@ metrics = { version = "^0.21", path = "../metrics", default-features = false }
 metrics-util = { version = "^0.15", path = "../metrics-util", default-features = false, features = ["summary"] }
 bytes = { version = "1", default-features = false }
 crossbeam-channel = { version = "0.5", default-features = false, features = ["std"] }
-prost = { version = "0.11", default-features = false }
-prost-types = { version = "0.11", default-features = false }
+prost = { version = "0.12", default-features = false }
+prost-types = { version = "0.12", default-features = false }
 tui = { version = "0.19", default-features = false, features = ["termion"] }
 termion = { version = "2", default-features = false }
 chrono = { version = "0.4", default-features = false, features = ["clock"] }
 
 [build-dependencies]
-prost-build = "0.11"
+prost-build = "0.12"
 home = "=0.5.5"
diff --git a/metrics-observer/src/metrics.rs b/metrics-observer/src/metrics.rs
index af5c8e72..59d78032 100644
--- a/metrics-observer/src/metrics.rs
+++ b/metrics-observer/src/metrics.rs
@@ -1,10 +1,13 @@
-use std::collections::{BTreeMap, HashMap};
 use std::io::Read;
 use std::net::TcpStream;
 use std::net::ToSocketAddrs;
 use std::sync::{Arc, Mutex, RwLock};
 use std::thread;
 use std::time::Duration;
+use std::{
+    collections::{BTreeMap, HashMap},
+    convert::TryFrom as _,
+};
 
 use bytes::{BufMut, BytesMut};
 use prost::Message;
@@ -178,7 +181,7 @@ impl Runner {
 
                         match event {
                             Event::Metadata(metadata) => {
-                                let metric_type = MetricType::from_i32(metadata.metric_type)
+                                let metric_type = MetricType::try_from(metadata.metric_type)
                                     .expect("unknown metric type over wire");
                                 let metric_kind = match metric_type {
                                     MetricType::Counter => MetricKind::Counter,