diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index d173104d6..cfeafaa55 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -60,7 +60,7 @@ export {
 export { ValidateUpgradeSafetyOptions, validateUpgradeSafety, ProjectReport, ReferenceContractNotFound } from './cli';
 
 export { getUpgradeInterfaceVersion } from './upgrade-interface-version';
-export { makeNamespacedInput } from './utils/make-namespaced';
+export { makeNamespacedInput, trySanitizeNatSpec } from './utils/make-namespaced';
 export { isNamespaceSupported } from './storage/namespace';
 export { inferProxyAdmin } from './infer-proxy-admin';
 export { assertUnreachable } from './utils/assert';
diff --git a/packages/core/src/utils/make-namespaced.test.ts b/packages/core/src/utils/make-namespaced.test.ts
index e236f3d57..a5448a9b8 100644
--- a/packages/core/src/utils/make-namespaced.test.ts
+++ b/packages/core/src/utils/make-namespaced.test.ts
@@ -6,7 +6,7 @@ import {
   TASK_COMPILE_SOLIDITY_RUN_SOLCJS,
 } from 'hardhat/builtin-tasks/task-names';
 
-import { makeNamespacedInput } from './make-namespaced';
+import { makeNamespacedInput, trySanitizeNatSpec } from './make-namespaced';
 import { SolcBuild } from 'hardhat/types/builtin-tasks';
 import { SolcInput, SolcOutput } from '../solc-api';
 import { BuildInfo } from 'hardhat/types';
@@ -40,11 +40,14 @@ async function testMakeNamespaced(
   // Inefficient, but we want to test that we don't actually modify the original input object
   const origInput = JSON.parse(JSON.stringify(origBuildInfo.input));
 
-  const modifiedInput = await makeNamespacedInput(
+  const modifiedInput = makeNamespacedInput(
     origBuildInfo.input,
     origBuildInfo.output,
-    keepAllNatSpec ? undefined : origBuildInfo.solcVersion,
+    origBuildInfo.solcVersion,
   );
+  if (!keepAllNatSpec) {
+    await trySanitizeNatSpec(modifiedInput, origBuildInfo.solcVersion);
+  }
 
   // Run hardhat compile on the modified input and make sure it has no errors
   const modifiedOutput = await hardhatCompile(modifiedInput, solcVersion);
diff --git a/packages/core/src/utils/make-namespaced.ts b/packages/core/src/utils/make-namespaced.ts
index 9d1a1b7a1..25f170a3f 100644
--- a/packages/core/src/utils/make-namespaced.ts
+++ b/packages/core/src/utils/make-namespaced.ts
@@ -34,14 +34,14 @@ const OUTPUT_SELECTION = {
  *
  * @param input The original solc input.
  * @param output The original solc output.
- * @param solcVersion The version of the solc compiler that was originally used to compile the input.
+ * @param _solcVersion The version of the solc compiler that was originally used to compile the input. This argument is no longer used and is kept for backwards compatibility.
  * @returns The modified solc input with storage layout that includes namespaced type information.
  */
-export async function makeNamespacedInput(
+export function makeNamespacedInput(
   input: SolcInput,
   output: SolcOutput,
-  solcVersion?: string,
-): Promise<SolcInput> {
+  _solcVersion?: string,
+): SolcInput {
   const modifiedSources: Record<string, { content?: string }> = {};
 
   for (const [sourcePath] of Object.entries(input.sources)) {
@@ -167,21 +167,36 @@ export async function makeNamespacedInput(
       }
     }
 
-    const modifiedSource = await tryRemoveNonStructNatSpec(getModifiedSource(orig, modifications), solcVersion);
-
-    modifiedSources[sourcePath] = { ...source, content: modifiedSource };
+    modifiedSources[sourcePath] = { ...source, content: getModifiedSource(orig, modifications) };
   }
 
   return { ...input, sources: modifiedSources, settings: { ...input.settings, outputSelection: OUTPUT_SELECTION } };
 }
 
 /**
- * If we have the compiler version available and Slang is supported for the current platform and compiler version,
- * use Slang to parse and remove all NatSpec comments that do not precede a struct definition and return the modified content.
+ * Attempts to remove all NatSpec comments that do not precede a struct definition from the input source contents.
+ * Directly modifies the input source contents.
+ *
+ * If the solc version is not supported by the parser, the original content is kept.
+ *
+ * @param solcInput Solc input.
+ * @param solcVersion The version of the solc compiler that was originally used to compile the input.
+ */
+export async function trySanitizeNatSpec(solcInput: SolcInput, solcVersion: string) {
+  for (const [sourcePath, source] of Object.entries(solcInput.sources)) {
+    if (source.content !== undefined) {
+      solcInput.sources[sourcePath].content = await tryRemoveNonStructNatSpec(source.content, solcVersion);
+    }
+  }
+}
+
+/**
+ * If Slang is supported for the current compiler version, use Slang to parse and remove all NatSpec comments
+ * that do not precede a struct definition and return the modified content.
  *
  * Otherwise, return the original content.
  */
-async function tryRemoveNonStructNatSpec(origContent: string, solcVersion: string | undefined): Promise<string> {
+async function tryRemoveNonStructNatSpec(origContent: string, solcVersion: string): Promise<string> {
   if (solcVersion === undefined) {
     return origContent;
   }
diff --git a/packages/plugin-hardhat/src/index.ts b/packages/plugin-hardhat/src/index.ts
index 37f9d6177..d30ef0d51 100644
--- a/packages/plugin-hardhat/src/index.ts
+++ b/packages/plugin-hardhat/src/index.ts
@@ -87,7 +87,7 @@ subtask(TASK_COMPILE_SOLIDITY, async (args: { force: boolean }, hre, runSuper) =
 });
 
 subtask(TASK_COMPILE_SOLIDITY_COMPILE, async (args: RunCompilerArgs, hre, runSuper) => {
-  const { isNamespaceSupported, validate, solcInputOutputDecoder, makeNamespacedInput } = await import(
+  const { isNamespaceSupported, validate, solcInputOutputDecoder, makeNamespacedInput, trySanitizeNatSpec } = await import(
     '@openzeppelin/upgrades-core'
   );
   const { writeValidations } = await import('./utils/validations.js');
@@ -101,7 +101,8 @@ subtask(TASK_COMPILE_SOLIDITY_COMPILE, async (args: RunCompilerArgs, hre, runSup
 
     let namespacedOutput = undefined;
     if (isNamespaceSupported(args.solcVersion)) {
-      const namespacedInput = await makeNamespacedInput(args.input, output, args.solcVersion);
+      const namespacedInput = makeNamespacedInput(args.input, output, args.solcVersion);
+      await trySanitizeNatSpec(namespacedInput, args.solcVersion);
       namespacedOutput = (await runSuper({ ...args, quiet: true, input: namespacedInput })).output;
 
       const namespacedCompileErrors = getNamespacedCompileErrors(namespacedOutput);