diff --git a/eo-parser/src/main/java/org/eolang/parser/StrictXmir.java b/eo-parser/src/main/java/org/eolang/parser/StrictXmir.java
index a91d450dc6..f1319f8be9 100644
--- a/eo-parser/src/main/java/org/eolang/parser/StrictXmir.java
+++ b/eo-parser/src/main/java/org/eolang/parser/StrictXmir.java
@@ -205,30 +205,46 @@ private static XML reset(final XML xml, final Path tmp) {
     private static File fetch(final String uri, final Path path, final Path tmp) {
         final File ret;
         if (StrictXmir.MINE.equals(uri)) {
-            if (path.toFile().getParentFile().mkdirs()) {
-                Logger.debug(StrictXmir.class, "Directory for %[file]s created", path);
-            }
-            try {
-                Files.write(
-                    path,
-                    new IoCheckedBytes(
-                        new BytesOf(new ResourceOf("XMIR.xsd"))
-                    ).asBytes()
-                );
-                Logger.debug(StrictXmir.class, "XSD copied to %[file]s", path);
-            } catch (final IOException ex) {
-                throw new IllegalArgumentException(
-                    String.format("Failed to save %s to %s", uri, path),
-                    ex
-                );
-            }
-            ret = path.toFile();
+            ret = StrictXmir.copied(uri, path, tmp);
         } else {
-            ret = StrictXmir.download(uri, path, tmp);
+            ret = StrictXmir.downloaded(uri, path, tmp);
         }
         return ret;
     }
 
+    /**
+     * Copy URI from local resource and save to file.
+     * @param uri The URI
+     * @param path The file
+     * @param tmp Directory to synchronize by
+     * @return Where it was saved
+     */
+    private static File copied(final String uri, final Path path, final Path tmp) {
+        final File file = path.toFile();
+        synchronized (tmp) {
+            if (!file.exists()) {
+                if (file.getParentFile().mkdirs()) {
+                    Logger.debug(StrictXmir.class, "Directory for %[file]s created", path);
+                }
+                try {
+                    Files.write(
+                        path,
+                        new IoCheckedBytes(
+                            new BytesOf(new ResourceOf("XMIR.xsd"))
+                        ).asBytes()
+                    );
+                    Logger.debug(StrictXmir.class, "XSD copied to %[file]s", path);
+                } catch (final IOException ex) {
+                    throw new IllegalArgumentException(
+                        String.format("Failed to save %s to %s", uri, path),
+                        ex
+                    );
+                }
+            }
+        }
+        return file;
+    }
+
     /**
      * Download URI from Internet and save to file.
      * @param uri The URI
@@ -237,7 +253,7 @@ private static File fetch(final String uri, final Path path, final Path tmp) {
      * @return Where it was saved
      */
     @SuppressWarnings("PMD.CognitiveComplexity")
-    private static File download(final String uri, final Path path, final Path tmp) {
+    private static File downloaded(final String uri, final Path path, final Path tmp) {
         final File abs = path.toFile().getAbsoluteFile();
         synchronized (tmp) {
             if (!abs.exists()) {
diff --git a/eo-parser/src/test/java/org/eolang/parser/StrictXmirTest.java b/eo-parser/src/test/java/org/eolang/parser/StrictXmirTest.java
index 6a5dc80745..1f822bb92f 100644
--- a/eo-parser/src/test/java/org/eolang/parser/StrictXmirTest.java
+++ b/eo-parser/src/test/java/org/eolang/parser/StrictXmirTest.java
@@ -138,6 +138,49 @@ void validatesXmirWithLocalSchema(@Mktmp final Path tmp) {
         );
     }
 
+    @RepeatedTest(20)
+    @ExtendWith(MktmpResolver.class)
+    void validatesXmirWithLocalSchemaInMultipleThreads(@Mktmp final Path tmp) {
+        Assertions.assertDoesNotThrow(
+            new Together<>(
+                thread -> new StrictXmir(
+                    new Xmir(
+                        StrictXmirTest.xmir(
+                            String.format(
+                                "https://www.eolang.org/xsd/XMIR-%s.xsd",
+                                Manifests.read("EO-Version")
+                            )
+                        )
+                    ),
+                    tmp
+                ).inner()
+            )::asList,
+            "validation should pass as normal"
+        );
+    }
+
+    @RepeatedTest(20)
+    @ExtendWith(MktmpResolver.class)
+    void validatesXmirWithLocalSchemaInMultipleThreadsWithTheSameXml(@Mktmp final Path tmp) {
+        final XML xml = new StrictXmir(
+            new Xmir(
+                StrictXmirTest.xmir(
+                    String.format(
+                        "https://www.eolang.org/xsd/XMIR-%s.xsd",
+                        Manifests.read("EO-Version")
+                    )
+                )
+            ),
+            tmp
+        );
+        Assertions.assertDoesNotThrow(
+            new Together<>(
+                thread -> xml.inner()
+            )::asList,
+            "validation should pass as normal"
+        );
+    }
+
     @Test
     @ExtendWith(MktmpResolver.class)
     void validatesXmirWithBrokenUri(@Mktmp final Path tmp) {