diff --git a/src/main/java/com/ldtteam/structurize/api/Utils.java b/src/main/java/com/ldtteam/structurize/api/Utils.java
index 7e7b6b969..b653f0525 100644
--- a/src/main/java/com/ldtteam/structurize/api/Utils.java
+++ b/src/main/java/com/ldtteam/structurize/api/Utils.java
@@ -8,6 +8,8 @@
 import org.jetbrains.annotations.NotNull;
 
 import java.io.File;
+import java.text.Normalizer;
+import java.util.Locale;
 import java.util.Objects;
 
 /**
@@ -73,4 +75,21 @@ public static boolean nbtContains(final CompoundTag originTag, final CompoundTag
         }
         return true;
     }
+
+    /**
+     * Get a filename that's probably safe from a player name that might contain problematic characters.
+     * @param input a player name or other possibly unsafe text.
+     * @return the safe filename.
+     *
+     * This doesn't protect against Windows reserved filenames. Most servers are Linux anyway
+     * so this only hurts SP players who will have a lot of Windows things break on them too.
+     */
+    public static String getSafePackName(String input)
+    {
+        String s = Normalizer.normalize(input, Normalizer.Form.NFC);
+        s = s.replaceAll("[\\\\/:*?\"<>|]", "_");
+        s = s.replaceAll("\\p{Cntrl}", "");
+        s = s.trim();
+        return s;
+    }
 }
diff --git a/src/main/java/com/ldtteam/structurize/client/gui/WindowShapeTool.java b/src/main/java/com/ldtteam/structurize/client/gui/WindowShapeTool.java
index 9209d2c54..53e4d76fa 100644
--- a/src/main/java/com/ldtteam/structurize/client/gui/WindowShapeTool.java
+++ b/src/main/java/com/ldtteam/structurize/client/gui/WindowShapeTool.java
@@ -8,6 +8,7 @@
 import com.ldtteam.blockui.views.View;
 import com.ldtteam.structurize.api.RotationMirror;
 import com.ldtteam.structurize.api.Shape;
+import com.ldtteam.structurize.api.Utils;
 import com.ldtteam.structurize.api.constants.Constants;
 import com.ldtteam.structurize.blueprints.v1.Blueprint;
 import com.ldtteam.structurize.blueprints.v1.BlueprintUtil;
@@ -332,13 +333,13 @@ protected void handlePlacement(final BuildToolPlacementMessage.HandlerType type,
         final BlueprintPreviewData previewData = RenderingCache.getOrCreateBlueprintPreviewData("shapes");
         if (previewData.getBlueprint() != null)
         {
-            final String packName = Minecraft.getInstance().getUser().getName();
+            final String packName = Utils.getSafePackName(Minecraft.getInstance().getUser().getName());
             final Path subpath = Path.of(
                 SHAPES_FOLDER,
                 shape.toString().toLowerCase(Locale.ROOT),
                 mainBlock.getItem().toString().replace(':', '_'),
                 secondaryBlock.getItem().toString().replace(':', '_'),
-                String.format("%dx%dx%dx%d_%c.blueprint", length, width, height, frequency, hollow ? 'h' : 'f'));
+                String.format("%sx%sx%sx%s_%c.blueprint", length, width, height, frequency, hollow ? 'h' : 'f'));
             final Path path = Minecraft.getInstance().gameDirectory.toPath()
                 .resolve(BLUEPRINT_FOLDER)
                 .resolve(packName.toLowerCase(Locale.US))
diff --git a/src/main/java/com/ldtteam/structurize/storage/ClientStructurePackLoader.java b/src/main/java/com/ldtteam/structurize/storage/ClientStructurePackLoader.java
index d285c467e..32e2c7d61 100644
--- a/src/main/java/com/ldtteam/structurize/storage/ClientStructurePackLoader.java
+++ b/src/main/java/com/ldtteam/structurize/storage/ClientStructurePackLoader.java
@@ -4,6 +4,7 @@
 import com.google.gson.JsonObject;
 import com.ldtteam.structurize.Structurize;
 import com.ldtteam.structurize.api.Log;
+import com.ldtteam.structurize.api.Utils;
 import com.ldtteam.structurize.api.constants.Constants;
 import com.ldtteam.structurize.network.messages.NotifyServerAboutStructurePacksMessage;
 import com.ldtteam.structurize.network.messages.SyncSettingsToServer;
@@ -101,7 +102,7 @@ public static void onClientLoading()
                     Files.createDirectory(outputPath);
                 }
 
-                final Path clientPackPath = outputPath.resolve(Minecraft.getInstance().getUser().getName().toLowerCase(Locale.US));
+                final Path clientPackPath = outputPath.resolve(Utils.getSafePackName(Minecraft.getInstance().getUser().getName()).toLowerCase(Locale.US));
                 if (!Files.exists(clientPackPath))
                 {
                     Files.createDirectory(clientPackPath);
@@ -345,12 +346,12 @@ public static Path zipSlipProtect(ZipEntry zipEntry, Path targetDir) throws IOEx
      */
     public static void handleSaveScanMessage(final CompoundTag compound, final String fileName, final HolderLookup.Provider provider)
     {
-        final String packName = Minecraft.getInstance().getUser().getName().toLowerCase(Locale.US);
-        StructurePacks.switchSelectedPack(StructurePacks.getStructurePack(Minecraft.getInstance().getUser().getName()));
+        final String packName = Utils.getSafePackName(Minecraft.getInstance().getUser().getName());
+        StructurePacks.switchSelectedPack(StructurePacks.getStructurePack(Utils.getSafePackName(Minecraft.getInstance().getUser().getName())));
         RenderingCache.getOrCreateBlueprintPreviewData("blueprint").setBlueprintFuture(
           StructurePacks.storeBlueprint(packName, compound, Minecraft.getInstance().gameDirectory.toPath()
             .resolve(BLUEPRINT_FOLDER)
-            .resolve(Minecraft.getInstance().getUser().getName().toLowerCase(Locale.US))
+            .resolve(packName.toLowerCase(Locale.US))
             .resolve(SCANS_FOLDER).resolve(fileName), provider));
         RenderingCache.getOrCreateBlueprintPreviewData("blueprint").setPos(null);
         Minecraft.getInstance().player.displayClientMessage(Component.translatable("Scan successfully saved as %s", fileName), false);