diff --git a/src/main/java/net/fabricmc/loom/configuration/providers/forge/MinecraftPatchedProvider.java b/src/main/java/net/fabricmc/loom/configuration/providers/forge/MinecraftPatchedProvider.java
index 7f242989..8946e99b 100644
--- a/src/main/java/net/fabricmc/loom/configuration/providers/forge/MinecraftPatchedProvider.java
+++ b/src/main/java/net/fabricmc/loom/configuration/providers/forge/MinecraftPatchedProvider.java
@@ -270,11 +270,13 @@ public class MinecraftPatchedProvider extends MergedMinecraftProvider {
 		Path tmpSrg = getToSrgMappings();
 		Set<File> mcLibs = getProject().getConfigurations().getByName(Constants.Configurations.MINECRAFT_DEPENDENCIES).resolve();
 
-		ThreadingUtils.run(() -> {
-			Files.copy(SpecialSourceExecutor.produceSrgJar(getExtension().getMcpConfigProvider().getRemapAction(), getProject(), "client", mcLibs, clientJar, tmpSrg), minecraftClientSrgJar.toPath());
-		}, () -> {
-			Files.copy(SpecialSourceExecutor.produceSrgJar(getExtension().getMcpConfigProvider().getRemapAction(), getProject(), "server", mcLibs, serverJar, tmpSrg), minecraftServerSrgJar.toPath());
-		});
+		// These can't be threaded because accessing getRemapAction().getMainClass() can cause a situation where
+		// 1. thread A has an FS open
+		// 2. thread B tries to open a new one, but fails
+		// 3. thread A closes its FS
+		// 4. thread B tries to get the already open one => crash
+		Files.copy(SpecialSourceExecutor.produceSrgJar(getExtension().getMcpConfigProvider().getRemapAction(), getProject(), "client", mcLibs, clientJar, tmpSrg), minecraftClientSrgJar.toPath());
+		Files.copy(SpecialSourceExecutor.produceSrgJar(getExtension().getMcpConfigProvider().getRemapAction(), getProject(), "server", mcLibs, serverJar, tmpSrg), minecraftServerSrgJar.toPath());
 	}
 
 	private Path getToSrgMappings() throws IOException {
diff --git a/src/main/java/net/fabricmc/loom/util/srg/SpecialSourceExecutor.java b/src/main/java/net/fabricmc/loom/util/srg/SpecialSourceExecutor.java
index 59392e94..300ae892 100644
--- a/src/main/java/net/fabricmc/loom/util/srg/SpecialSourceExecutor.java
+++ b/src/main/java/net/fabricmc/loom/util/srg/SpecialSourceExecutor.java
@@ -57,7 +57,7 @@ public class SpecialSourceExecutor {
 	}
 
 	public static Path produceSrgJar(RemapAction remapAction, Project project, String side, Set<File> mcLibs, Path officialJar, Path mappings)
-			throws Exception {
+			throws IOException {
 		Set<String> filter = Files.readAllLines(mappings, StandardCharsets.UTF_8).stream()
 				.filter(s -> !s.startsWith("\t"))
 				.map(s -> s.split(" ")[0] + ".class")