diff --git a/libs/compute_api/src/spec.rs b/libs/compute_api/src/spec.rs
index 19e5d60ea3..3a4060e9a8 100644
--- a/libs/compute_api/src/spec.rs
+++ b/libs/compute_api/src/spec.rs
@@ -457,7 +457,7 @@ pub struct JwksSettings {
 }
 
 /// Protocol used to connect to a Pageserver. Parsed from the connstring scheme.
-#[derive(Clone, Copy, Debug, Default)]
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
 pub enum PageserverProtocol {
     /// The original protocol based on libpq and COPY. Uses postgresql:// or postgres:// scheme.
     #[default]
diff --git a/pageserver/client_grpc/Cargo.toml b/pageserver/client_grpc/Cargo.toml
index 0e9bf9ccdf..a4ab4a9a3b 100644
--- a/pageserver/client_grpc/Cargo.toml
+++ b/pageserver/client_grpc/Cargo.toml
@@ -11,9 +11,16 @@ http.workspace = true
 thiserror.workspace = true
 tonic.workspace = true
 tracing.workspace = true
-tokio = { version = "1.43.1", features = ["full", "macros", "net", "io-util", "rt", "rt-multi-thread"] }
+tokio = { version = "1.43.1", features = [
+    "full",
+    "macros",
+    "net",
+    "io-util",
+    "rt",
+    "rt-multi-thread",
+] }
 uuid = { version = "1", features = ["v4"] }
-tower = {  version = "0.4", features = ["timeout", "util"] }
+tower = { version = "0.4", features = ["timeout", "util"] }
 rand = "0.8"
 tokio-util = { version = "0.7", features = ["compat"] }
 hyper-util = "0.1.9"
@@ -25,6 +32,7 @@ async-trait = { version = "0.1" }
 tokio-stream = "0.1"
 dashmap = "5"
 chrono = { version = "0.4", features = ["serde"] }
+compute_api.workspace = true
 
 
 pageserver_page_api.workspace = true
diff --git a/pageserver/client_grpc/src/client.rs b/pageserver/client_grpc/src/client.rs
index 3e4da72715..ad2ee18761 100644
--- a/pageserver/client_grpc/src/client.rs
+++ b/pageserver/client_grpc/src/client.rs
@@ -2,6 +2,7 @@ use std::collections::HashMap;
 use std::sync::Arc;
 
 use anyhow::{anyhow, ensure};
+use compute_api::spec::PageserverProtocol;
 use pageserver_page_api as page_api;
 use tokio::time::Instant;
 use tracing::{error, info, instrument, warn};
@@ -28,7 +29,8 @@ pub struct PageserverClient {
 }
 
 impl PageserverClient {
-    /// Creates a new Pageserver client.
+    /// Creates a new Pageserver client for a given tenant and timeline. Uses the Pageservers given
+    /// in the shard map, which must be complete and must use gRPC URLs.
     pub fn new(
         tenant_id: TenantId,
         timeline_id: TimelineId,
@@ -334,6 +336,11 @@ impl Shard {
         shard_id: ShardIndex,
         auth_token: Option<String>,
     ) -> anyhow::Result<Self> {
+        // Sanity-check that the URL uses gRPC.
+        if PageserverProtocol::from_connstring(&url)? != PageserverProtocol::Grpc {
+            return Err(anyhow!("invalid shard URL {url}: must use gRPC"));
+        }
+
         // Use a common channel pool for all clients, to multiplex unary and stream requests across
         // the same TCP connections. The channel pool is unbounded (but client pools are bounded).
         let channel_pool = ChannelPool::new(url)?;