diff --git a/packages/angular/src/executors/ng-packagr-lite/ng-packagr-adjustments/ngc/compile-source-files.ts b/packages/angular/src/executors/ng-packagr-lite/ng-packagr-adjustments/ngc/compile-source-files.ts
index 48bf448878..6e133342e5 100644
--- a/packages/angular/src/executors/ng-packagr-lite/ng-packagr-adjustments/ngc/compile-source-files.ts
+++ b/packages/angular/src/executors/ng-packagr-lite/ng-packagr-adjustments/ngc/compile-source-files.ts
@@ -154,6 +154,7 @@ export async function compileSourceFiles(
   for (const sourceFile of builder.getSourceFiles()) {
     if (!ignoreForDiagnostics.has(sourceFile)) {
       allDiagnostics.push(
+        ...builder.getDeclarationDiagnostics(sourceFile),
         ...builder.getSyntacticDiagnostics(sourceFile),
         ...builder.getSemanticDiagnostics(sourceFile)
       );
diff --git a/packages/angular/src/executors/package/ng-packagr-adjustments/ngc/compile-source-files.ts b/packages/angular/src/executors/package/ng-packagr-adjustments/ngc/compile-source-files.ts
index 01be8118e8..e38ba18d59 100644
--- a/packages/angular/src/executors/package/ng-packagr-adjustments/ngc/compile-source-files.ts
+++ b/packages/angular/src/executors/package/ng-packagr-adjustments/ngc/compile-source-files.ts
@@ -151,6 +151,7 @@ export async function compileSourceFiles(
   for (const sourceFile of builder.getSourceFiles()) {
     if (!ignoreForDiagnostics.has(sourceFile)) {
       allDiagnostics.push(
+        ...builder.getDeclarationDiagnostics(sourceFile),
         ...builder.getSyntacticDiagnostics(sourceFile),
         ...builder.getSemanticDiagnostics(sourceFile)
       );