diff --git a/forge/src/main/java/org/embeddedt/modernfix/forge/mixin/bugfix/unsafe_modded_shape_caches/ShapeCacheCyclicMixin.java b/forge/src/main/java/org/embeddedt/modernfix/forge/mixin/bugfix/unsafe_modded_shape_caches/ShapeCacheCyclicMixin.java
new file mode 100644
index 00000000..3f1eb8e2
--- /dev/null
+++ b/forge/src/main/java/org/embeddedt/modernfix/forge/mixin/bugfix/unsafe_modded_shape_caches/ShapeCacheCyclicMixin.java
@@ -0,0 +1,27 @@
+package org.embeddedt.modernfix.forge.mixin.bugfix.unsafe_modded_shape_caches;
+
+import org.embeddedt.modernfix.ModernFix;
+import org.embeddedt.modernfix.annotation.RequiresMod;
+import org.spongepowered.asm.mixin.*;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * see {@link ShapeCacheRSMixin}
+ */
+@Pseudo
+@Mixin(targets = { "com/lothrazar/cyclic/block/cable/ShapeCache" }, remap = false)
+@RequiresMod("cyclic")
+@SuppressWarnings("rawtypes")
+public class ShapeCacheCyclicMixin {
+    @Shadow @Final @Mutable private static final Map CACHE = new ConcurrentHashMap();
+
+    @Inject(method = "<clinit>", at = @At("RETURN"))
+    private static void mfix$notify(CallbackInfo ci) {
+        ModernFix.LOGGER.info("Made Cyclic shape cache map thread-safe");
+    }
+}
diff --git a/forge/src/main/java/org/embeddedt/modernfix/forge/mixin/bugfix/unsafe_modded_shape_caches/ShapeCacheRSMixin.java b/forge/src/main/java/org/embeddedt/modernfix/forge/mixin/bugfix/unsafe_modded_shape_caches/ShapeCacheRSMixin.java
new file mode 100644
index 00000000..c2a43839
--- /dev/null
+++ b/forge/src/main/java/org/embeddedt/modernfix/forge/mixin/bugfix/unsafe_modded_shape_caches/ShapeCacheRSMixin.java
@@ -0,0 +1,29 @@
+package org.embeddedt.modernfix.forge.mixin.bugfix.unsafe_modded_shape_caches;
+
+import org.embeddedt.modernfix.ModernFix;
+import org.embeddedt.modernfix.annotation.RequiresMod;
+import org.spongepowered.asm.mixin.*;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * Some mods use a custom shape cache with a non-thread-safe map. There is no reason why this wouldn't cause crashes
+ * in vanilla as well if getShape was called on two threads at once. It seems more likely to happen with ModernFix
+ * installed due to the dynamic blockstate cache generation, so we solve it by making the maps thread-safe.
+ */
+@Pseudo
+@Mixin(targets = { "com/refinedmods/refinedstorage/block/shape/ShapeCache" }, remap = false)
+@RequiresMod("refinedstorage")
+@SuppressWarnings("rawtypes")
+public class ShapeCacheRSMixin {
+    @Shadow @Final @Mutable private static final Map CACHE = new ConcurrentHashMap();
+
+    @Inject(method = "<clinit>", at = @At("RETURN"))
+    private static void mfix$notify(CallbackInfo ci) {
+        ModernFix.LOGGER.info("Made Refined Storage shape cache map thread-safe");
+    }
+}