diff --git a/src/main/java/org/embeddedt/modernfix/common/mixin/bugfix/buffer_builder_leak/RenderBuffersMixin.java b/src/main/java/org/embeddedt/modernfix/common/mixin/bugfix/buffer_builder_leak/RenderBuffersMixin.java
new file mode 100644
index 00000000..feb4a015
--- /dev/null
+++ b/src/main/java/org/embeddedt/modernfix/common/mixin/bugfix/buffer_builder_leak/RenderBuffersMixin.java
@@ -0,0 +1,27 @@
+package org.embeddedt.modernfix.common.mixin.bugfix.buffer_builder_leak;
+
+import com.mojang.blaze3d.vertex.BufferBuilder;
+import it.unimi.dsi.fastutil.objects.Object2ObjectLinkedOpenHashMap;
+import net.minecraft.client.renderer.RenderBuffers;
+import net.minecraft.client.renderer.RenderType;
+import org.embeddedt.modernfix.annotation.ClientOnlyMixin;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+@Mixin(RenderBuffers.class)
+@ClientOnlyMixin
+public class RenderBuffersMixin {
+    /**
+     * @author embeddedt
+     * @reason put() may be called for multiple instances of the same render type (e.g. signSheet and hangingSignSheet
+     * in 1.20.1). This leaks the previous BufferBuilder if one is already in the map.
+     */
+    @Inject(method = "put", at = @At("HEAD"), cancellable = true)
+    private static void mfix$preventBufferLeak(Object2ObjectLinkedOpenHashMap<RenderType, BufferBuilder> mapBuilders, RenderType renderType, CallbackInfo ci) {
+        if (mapBuilders.containsKey(renderType)) {
+            ci.cancel();
+        }
+    }
+}