diff --git a/crates/fbuild-build-esp/src/esp32/mod.rs b/crates/fbuild-build-esp/src/esp32/mod.rs
index f7095f661..ac79c6868 100644
--- a/crates/fbuild-build-esp/src/esp32/mod.rs
+++ b/crates/fbuild-build-esp/src/esp32/mod.rs
@@ -28,6 +28,17 @@ impl crate::PlatformSupport for Esp32PlatformSupport {
         orchestrator::provision_esp32(inputs, mode).await
     }
 
+    /// The Arduino core bundles libraries (FS, WiFi, ESPmDNS, ...) that
+    /// `lib_deps` may name; the build filters them out before downloading,
+    /// so provisioning must too (FastLED/fbuild#1442).
+    fn downloadable_lib_deps(
+        &self,
+        inputs: &crate::provision::ProvisionInputs<'_>,
+        lib_deps: Vec<String>,
+    ) -> Vec<String> {
+        orchestrator::downloadable_lib_deps(inputs, lib_deps)
+    }
+
     fn default_board_id(&self) -> &str {
         "esp32dev"
     }
diff --git a/crates/fbuild-build-esp/src/esp32/orchestrator/build.rs b/crates/fbuild-build-esp/src/esp32/orchestrator/build.rs
index d7e25f0d3..5ae32286b 100644
--- a/crates/fbuild-build-esp/src/esp32/orchestrator/build.rs
+++ b/crates/fbuild-build-esp/src/esp32/orchestrator/build.rs
@@ -295,7 +295,18 @@ impl BuildOrchestrator for Esp32Orchestrator {
         }
 
         // 8.5. Library dependencies
-        let lib_deps = ctx.config.get_lib_deps(&params.env_name)?;
+        //
+        // `lib_deps` may name libraries the Arduino core bundles (`FS`,
+        // `ArduinoOTA`, `ESPmDNS`, ...), as PlatformIO allows. Those are
+        // already on the include path above and compiled with the framework,
+        // so drop them rather than sending them to the registry, which does
+        // not carry them (FastLED/fbuild#1442). RP2040 does the same.
+        let lib_deps = fbuild_library_select::external_declared_deps(
+            &ctx.config.get_lib_deps(&params.env_name)?,
+            &fbuild_packages::library::framework_library::discover_framework_libraries(
+                &builtin_libs_dir,
+            ),
+        );
         let lib_ignore = ctx.config.get_lib_ignore(&params.env_name)?;
 
         use fbuild_packages::Toolchain;
diff --git a/crates/fbuild-build-esp/src/esp32/orchestrator/mod.rs b/crates/fbuild-build-esp/src/esp32/orchestrator/mod.rs
index ea478d2f0..32ca57f8b 100644
--- a/crates/fbuild-build-esp/src/esp32/orchestrator/mod.rs
+++ b/crates/fbuild-build-esp/src/esp32/orchestrator/mod.rs
@@ -34,7 +34,7 @@ mod helpers;
 mod local_libs;
 mod packages;
 
-pub(crate) use packages::provision_esp32;
+pub(crate) use packages::{downloadable_lib_deps, provision_esp32};
 
 #[cfg(test)]
 mod tests;
diff --git a/crates/fbuild-build-esp/src/esp32/orchestrator/packages.rs b/crates/fbuild-build-esp/src/esp32/orchestrator/packages.rs
index b28b27cdc..4f0b81d30 100644
--- a/crates/fbuild-build-esp/src/esp32/orchestrator/packages.rs
+++ b/crates/fbuild-build-esp/src/esp32/orchestrator/packages.rs
@@ -626,3 +626,35 @@ async fn provision_esptool(
     row.duration_ms = started.elapsed().as_millis() as u64;
     Some(row)
 }
+
+/// Drop `lib_deps` entries the installed Arduino core bundles (`FS`,
+/// `ArduinoOTA`, `ESPmDNS`, ...), exactly as the build does, so `fbuild
+/// install` does not send them to the registry (FastLED/fbuild#1442).
+/// Without an installed platform and framework there is nothing to compare
+/// against, and every entry is returned.
+pub(crate) fn downloadable_lib_deps(
+    inputs: &ProvisionInputs<'_>,
+    lib_deps: Vec<String>,
+) -> Vec<String> {
+    use fbuild_packages::{Framework as _, Package as _};
+    let env_config = Some(inputs.env_config);
+    let platform = pioarduino_platform(inputs.project_dir, env_config);
+    if !platform.is_installed() {
+        return lib_deps;
+    }
+    let framework = pioarduino_framework(
+        &platform,
+        inputs.project_dir,
+        inputs.board.mcu.as_str(),
+        env_config,
+    );
+    if !framework.is_installed() {
+        return lib_deps;
+    }
+    fbuild_library_select::external_declared_deps(
+        &lib_deps,
+        &fbuild_packages::library::framework_library::discover_framework_libraries(
+            &framework.get_libraries_dir(),
+        ),
+    )
+}
diff --git a/crates/fbuild-library-select/src/lib_tests.rs b/crates/fbuild-library-select/src/lib_tests.rs
index 0c3dced76..9616692dc 100644
--- a/crates/fbuild-library-select/src/lib_tests.rs
+++ b/crates/fbuild-library-select/src/lib_tests.rs
@@ -621,3 +621,32 @@ fn declared_dep_name_normalization() {
     assert_eq!(declared_dep_name("https://example.com/x.git"), None);
     assert_eq!(declared_dep_name("./local"), None);
 }
+
+#[test]
+fn esp32_core_bundled_lib_deps_are_not_sent_to_the_registry() {
+    // FastLED/fbuild#1442: arduino-esp32 ships FS, ArduinoOTA and ESPmDNS in
+    // its `libraries/`; naming them in lib_deps must not reach the registry,
+    // while real registry and git dependencies still do.
+    let tmp = tempdir();
+    let libraries = vec![
+        lib(tmp.path(), "FS"),
+        lib(tmp.path(), "ArduinoOTA"),
+        lib(tmp.path(), "ESPmDNS"),
+        lib(tmp.path(), "WiFi"),
+    ];
+    let declared = vec![
+        "https://github.com/dvarrel/AsyncTCP".to_string(),
+        "bblanchon/ArduinoJson".to_string(),
+        "FS".to_string(),
+        "ArduinoOTA".to_string(),
+        "ESPmDNS".to_string(),
+    ];
+
+    assert_eq!(
+        external_declared_deps(&declared, &libraries),
+        vec![
+            "https://github.com/dvarrel/AsyncTCP".to_string(),
+            "bblanchon/ArduinoJson".to_string(),
+        ]
+    );
+}