diff --git a/.changeset/seven-chairs-hammer.md b/.changeset/seven-chairs-hammer.md
new file mode 100644
index 0000000000..a76badd741
--- /dev/null
+++ b/.changeset/seven-chairs-hammer.md
@@ -0,0 +1,5 @@
+---
+"@pnpm/core": patch
+---
+
+Don't fail on skipped optional dependencies, when searching for dependencies that should be built.
diff --git a/pkg-manager/core/src/install/index.ts b/pkg-manager/core/src/install/index.ts
index 70b29624f5..1bc97b329c 100644
--- a/pkg-manager/core/src/install/index.ts
+++ b/pkg-manager/core/src/install/index.ts
@@ -1419,8 +1419,9 @@ const _installInContext: InstallFunction = async (projects, ctx, opts) => {
   await waitTillAllFetchingsFinish()
   const depsRequiringBuild: DepPath[] = []
   if (opts.returnListOfDepsRequiringBuild) {
-    await Promise.all(Object.entries(dependenciesGraph).map(async ([depPath, { fetching }]) => {
-      const { files } = await fetching()
+    await Promise.all(Object.entries(dependenciesGraph).map(async ([depPath, node]) => {
+      if (node == null) return // We cannot detect if a skipped optional dependency requires build
+      const { files } = await node.fetching()
       if (files.requiresBuild) {
         depsRequiringBuild.push(depPath as DepPath)
       }