diff --git a/launcher/modplatform/flame/FlameInstanceCreationTask.cpp b/launcher/modplatform/flame/FlameInstanceCreationTask.cpp
index ef552c3c2..a1f10c156 100644
--- a/launcher/modplatform/flame/FlameInstanceCreationTask.cpp
+++ b/launcher/modplatform/flame/FlameInstanceCreationTask.cpp
@@ -537,7 +537,12 @@ void FlameCreationTask::setupDownloadJob(QEventLoop& loop)
         selectedOptionalMods = optionalModDialog.getResult();
     }
     for (const auto& result : results) {
-        auto relpath = FS::PathCombine(result.targetFolder, result.fileName);
+        auto fileName = result.fileName;
+#ifdef Q_OS_WIN
+        fileName = FS::RemoveInvalidPathChars(fileName);
+#endif
+        auto relpath = FS::PathCombine(result.targetFolder, fileName);
+
         if (!result.required && !selectedOptionalMods.contains(relpath)) {
             relpath += ".disabled";
         }
diff --git a/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.cpp b/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.cpp
index a688cea87..3b875103b 100644
--- a/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.cpp
+++ b/launcher/modplatform/modrinth/ModrinthInstanceCreationTask.cpp
@@ -240,11 +240,15 @@ bool ModrinthCreationTask::createInstance()
     auto root_modpack_url = QUrl::fromLocalFile(root_modpack_path);
 
     for (auto file : m_files) {
-        auto file_path = FS::PathCombine(root_modpack_path, file.path);
+        auto fileName = file.path;
+#ifdef Q_OS_WIN
+        fileName = FS::RemoveInvalidPathChars(fileName);
+#endif
+        auto file_path = FS::PathCombine(root_modpack_path, fileName);
         if (!root_modpack_url.isParentOf(QUrl::fromLocalFile(file_path))) {
             // This means we somehow got out of the root folder, so abort here to prevent exploits
             setError(tr("One of the files has a path that leads to an arbitrary location (%1). This is a security risk and isn't allowed.")
-                         .arg(file.path));
+                         .arg(fileName));
             return false;
         }
 
diff --git a/launcher/net/HttpMetaCache.cpp b/launcher/net/HttpMetaCache.cpp
index f37bc0bf8..648155412 100644
--- a/launcher/net/HttpMetaCache.cpp
+++ b/launcher/net/HttpMetaCache.cpp
@@ -84,6 +84,9 @@ auto HttpMetaCache::getEntry(QString base, QString resource_path) -> MetaEntryPt
 
 auto HttpMetaCache::resolveEntry(QString base, QString resource_path, QString expected_etag) -> MetaEntryPtr
 {
+#ifdef Q_OS_WIN
+    resource_path = FS::RemoveInvalidPathChars(resource_path);
+#endif
     auto entry = getEntry(base, resource_path);
     // it's not present? generate a default stale entry
     if (!entry) {