diff --git a/build.gradle b/build.gradle
index c67fd507..0115827b 100644
--- a/build.gradle
+++ b/build.gradle
@@ -92,12 +92,11 @@ dependencies {
 	}
 
 	// tinyfile management
-	implementation ('dev.architectury:tiny-remapper:1.3.11')
-	implementation ('dev.architectury:mappings-layers-core:1.4.9')
+	implementation ('dev.architectury:tiny-remapper:1.4.12')
 	implementation 'net.fabricmc:access-widener:2.0.0'
 	implementation 'net.fabricmc:mapping-io:0.2.1'
 
-	implementation ('net.fabricmc:lorenz-tiny:4.0.0') {
+	implementation ('net.fabricmc:lorenz-tiny:4.0.1') {
 		transitive = false
 	}
 	implementation "dev.architectury:refmap-remapper:1.0.5"
diff --git a/src/main/java/net/fabricmc/loom/util/TinyRemapperHelper.java b/src/main/java/net/fabricmc/loom/util/TinyRemapperHelper.java
index 5a50047a..12eb9185 100644
--- a/src/main/java/net/fabricmc/loom/util/TinyRemapperHelper.java
+++ b/src/main/java/net/fabricmc/loom/util/TinyRemapperHelper.java
@@ -28,6 +28,7 @@ import java.io.File;
 import java.io.IOException;
 import java.nio.file.Path;
 import java.util.Map;
+import java.util.regex.Pattern;
 
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
@@ -48,6 +49,11 @@ public final class TinyRemapperHelper {
 			.put("javax/annotation/concurrent/Immutable", "org/jetbrains/annotations/Unmodifiable")
 			.build();
 
+	/**
+	 * Matches the new local variable naming format introduced in 21w37a.
+	 */
+	private static final Pattern MC_LV_PATTERN = Pattern.compile("\\$\\$\\d+");
+
 	private TinyRemapperHelper() {
 	}
 
@@ -81,7 +87,8 @@ public final class TinyRemapperHelper {
 			builder.fixPackageAccess(true);
 		}
 
-		return builder.build();
+		return builder.invalidLvNamePattern(MC_LV_PATTERN)
+				.build();
 	}
 
 	public static TinyRemapper getTinyRemapper(Project project) throws IOException {
diff --git a/src/test/groovy/net/fabricmc/loom/test/integration/FabricAPITest.groovy b/src/test/groovy/net/fabricmc/loom/test/integration/FabricAPITest.groovy
index 1ad80e87..7c1246b5 100644
--- a/src/test/groovy/net/fabricmc/loom/test/integration/FabricAPITest.groovy
+++ b/src/test/groovy/net/fabricmc/loom/test/integration/FabricAPITest.groovy
@@ -44,7 +44,7 @@ class FabricAPITest extends Specification implements GradleProjectTestTrait {
 		setup:
 			def gradle = gradleProject(
 					repo: "https://github.com/FabricMC/fabric.git",
-					commit: "fc40aa9d88e9457957bdf3f8cec9698846828cd3",
+					commit: "46582230fb580d4c1f71e4b0737df27417ec9cb1",
 					version: version,
 					patch: "fabric_api"
 			)