diff --git a/CHANGELOG.md b/CHANGELOG.md
index da551cc1..0d64777f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -95,6 +95,7 @@ The **"Breaking Changes"** listed below are changes that have been made in the d
 - Fix bug where layout json and blockdata could be saved separately leading to inconsistent data.
 - Fix crash when saving tilesets with fewer palettes than the maximum.
 - Fix projects not opening on Windows if the project filepath contains certain characters.
+- Fix custom project filepaths not converting Windows file separators.
 - Fix exported tile images containing garbage pixels after the end of the tiles.
 - Fix fully transparent pixels rendering with the incorrect color.
 - Fix the values for some config fields shuffling their order every save.
diff --git a/src/config.cpp b/src/config.cpp
index d74adbcb..42a59149 100644
--- a/src/config.cpp
+++ b/src/config.cpp
@@ -984,7 +984,7 @@ void ProjectConfig::setFilePath(const QString &pathId, const QString &path) {
 }
 
 QString ProjectConfig::getCustomFilePath(ProjectFilePath pathId) {
-    return this->filePaths.value(pathId);
+    return QDir::cleanPath(this->filePaths.value(pathId));
 }
 
 QString ProjectConfig::getCustomFilePath(const QString &pathId) {
@@ -992,14 +992,17 @@ QString ProjectConfig::getCustomFilePath(const QString &pathId) {
 }
 
 QString ProjectConfig::getFilePath(ProjectFilePath pathId) {
-    const QString customPath = this->getCustomFilePath(pathId);
+    QString customPath = this->getCustomFilePath(pathId);
     if (!customPath.isEmpty()) {
         // A custom filepath has been specified. If the file/folder exists, use that.
-        const QString absCustomPath = this->projectDir + QDir::separator() + customPath;
-        if (QFileInfo::exists(absCustomPath)) {
+        const QString baseDir = this->projectDir + "/";
+        if (customPath.startsWith(baseDir)) {
+            customPath.remove(0, baseDir.length());
+        }
+        if (QFileInfo::exists(QDir::cleanPath(baseDir + customPath))) {
             return customPath;
         } else {
-            logError(QString("Custom project filepath '%1' not found. Using default.").arg(absCustomPath));
+            logError(QString("Custom project filepath '%1' not found. Using default.").arg(customPath));
         }
     }
     return defaultPaths.contains(pathId) ? defaultPaths[pathId].second : QString();
diff --git a/src/ui/customscriptseditor.cpp b/src/ui/customscriptseditor.cpp
index c3c412c2..eddbc7ae 100644
--- a/src/ui/customscriptseditor.cpp
+++ b/src/ui/customscriptseditor.cpp
@@ -11,7 +11,7 @@
 CustomScriptsEditor::CustomScriptsEditor(QWidget *parent) :
     QMainWindow(parent),
     ui(new Ui::CustomScriptsEditor),
-    baseDir(userConfig.projectDir + QDir::separator())
+    baseDir(userConfig.projectDir + "/")
 {
     ui->setupUi(this);
     setAttribute(Qt::WA_DeleteOnClose);
diff --git a/src/ui/projectsettingseditor.cpp b/src/ui/projectsettingseditor.cpp
index fa84f3e0..34987914 100644
--- a/src/ui/projectsettingseditor.cpp
+++ b/src/ui/projectsettingseditor.cpp
@@ -20,7 +20,7 @@ ProjectSettingsEditor::ProjectSettingsEditor(QWidget *parent, Project *project)
     QMainWindow(parent),
     ui(new Ui::ProjectSettingsEditor),
     project(project),
-    baseDir(projectConfig.projectDir + QDir::separator())
+    baseDir(projectConfig.projectDir + "/")
 {
     ui->setupUi(this);
     setAttribute(Qt::WA_DeleteOnClose);
@@ -388,7 +388,7 @@ QString ProjectSettingsEditor::chooseProjectFile(const QString &defaultFilepath)
     QString path;
     if (defaultFilepath.endsWith("/")){
         // Default filepath is a folder, choose a new folder
-        path = FileDialog::getExistingDirectory(this, "Choose Project File Folder", startDir) + QDir::separator();
+        path = FileDialog::getExistingDirectory(this, "Choose Project File Folder", startDir) + "/";
     } else{
         // Default filepath is not a folder, choose a new file
         path = FileDialog::getOpenFileName(this, "Choose Project File", startDir);