diff --git a/third_party/rust/rust.MODULE.bazel b/third_party/rust/rust.MODULE.bazel
index 1677a9a8b1d42..ae567cb708560 100644
--- a/third_party/rust/rust.MODULE.bazel
+++ b/third_party/rust/rust.MODULE.bazel
@@ -76,6 +76,11 @@ crate.from_cargo(
     name = "crate_index",
     cargo_lockfile = "//third_party/rust:Cargo.lock",
     manifests = ["//third_party/rust:Cargo.toml"],
+    # By default rules_rust will analyze dependencies for all supported target triples, which is very slow.
+    # Restrict to ones that we're interested in. See https://github.com/bazelbuild/rules_rust/issues/2876
+    supported_platform_triples = [
+        "x86_64-unknown-linux-gnu",
+    ],
 )
 crate.annotation(
     crate = "libudev-sys",
@@ -124,6 +129,9 @@ crate.from_cargo(
     name = "mdbook_index",
     cargo_lockfile = "//third_party/mdbook:Cargo.lock",
     manifests = ["//third_party/mdbook:Cargo.toml"],
+    supported_platform_triples = [
+        "x86_64-unknown-linux-gnu",
+    ],
 )
 crate.annotation(
     crate = "mdbook",
diff --git a/third_party/tock/tock.MODULE.bazel b/third_party/tock/tock.MODULE.bazel
index 6272af8b5cbf6..e7bd314f52924 100644
--- a/third_party/tock/tock.MODULE.bazel
+++ b/third_party/tock/tock.MODULE.bazel
@@ -9,6 +9,9 @@ crate.from_cargo(
     name = "tock_index",
     cargo_lockfile = "//third_party/tock:Cargo.lock",
     manifests = ["//third_party/tock:Cargo.toml"],
+    supported_platform_triples = [
+        "riscv32imc-unknown-none-elf",
+    ],
 )
 use_repo(crate, "tock_index")
 
@@ -17,6 +20,9 @@ crate.from_cargo(
     name = "elf2tab_index",
     cargo_lockfile = "@elf2tab//:Cargo.lock",
     manifests = ["@elf2tab//:Cargo.toml"],
+    supported_platform_triples = [
+        "x86_64-unknown-linux-gnu",
+    ],
 )
 use_repo(crate, "elf2tab_index")