diff --git a/src/main/java/net/fabricmc/loader/impl/launch/knot/KnotClassDelegate.java b/src/main/java/net/fabricmc/loader/impl/launch/knot/KnotClassDelegate.java
index 3e7e75f1d..3e5d301d5 100644
--- a/src/main/java/net/fabricmc/loader/impl/launch/knot/KnotClassDelegate.java
+++ b/src/main/java/net/fabricmc/loader/impl/launch/knot/KnotClassDelegate.java
@@ -512,10 +512,7 @@ private static boolean hasRegularCodeSource(URL url) {
 
 	private static Path getCodeSource(URL url, String fileName) {
 		try {
-			Path ret = UrlUtil.getCodeSource(url, fileName);
-			assert ret.equals(LoaderUtil.normalizeExistingPath(ret)); // ret should already be normalized
-
-			return ret;
+			return LoaderUtil.normalizeExistingPath(UrlUtil.getCodeSource(url, fileName));
 		} catch (UrlConversionException e) {
 			throw ExceptionUtil.wrap(e);
 		}
diff --git a/src/main/java/net/fabricmc/loader/impl/util/LoaderUtil.java b/src/main/java/net/fabricmc/loader/impl/util/LoaderUtil.java
index 170234a47..82f9f8235 100644
--- a/src/main/java/net/fabricmc/loader/impl/util/LoaderUtil.java
+++ b/src/main/java/net/fabricmc/loader/impl/util/LoaderUtil.java
@@ -24,9 +24,13 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 import java.util.stream.Collectors;
 
 public final class LoaderUtil {
+	private static final ConcurrentMap<Path, Path> pathNormalizationCache = new ConcurrentHashMap<>();
+
 	public static String getClassFileName(String className) {
 		return className.replace('.', '/').concat(".class");
 	}
@@ -40,6 +44,10 @@ public static Path normalizePath(Path path) {
 	}
 
 	public static Path normalizeExistingPath(Path path) {
+		return pathNormalizationCache.computeIfAbsent(path, LoaderUtil::normalizeExistingPath0);
+	}
+
+	private static Path normalizeExistingPath0(Path path) {
 		try {
 			return path.toRealPath();
 		} catch (IOException e) {