diff --git a/src/platform/guimac.mm b/src/platform/guimac.mm
index 47d67e0..55116ea 100644
--- a/src/platform/guimac.mm
+++ b/src/platform/guimac.mm
@@ -1443,6 +1443,12 @@ static SSApplicationDelegate *ssDelegate;
 
 std::vector<std::string> InitGui(int argc, char **argv) {
     std::vector<std::string> args = InitCli(argc, argv);
+    if(args.size() >= 2 && args[1].find("-psn_") == 0) {
+        // For unknown reasons, Finder passes a Carbon PSN (Process Serial Number) argument
+        // when a freshly downloaded application is run for the first time. Remove it so
+        // that it isn't interpreted as a filename.
+        args.erase(args.begin() + 1);
+    }
 
     ssDelegate = [[SSApplicationDelegate alloc] init];
     NSApplication.sharedApplication.delegate = ssDelegate;