diff --git a/src/slic3r/Utils/Process.cpp b/src/slic3r/Utils/Process.cpp
index bc6961f9a..1199e5e76 100644
--- a/src/slic3r/Utils/Process.cpp
+++ b/src/slic3r/Utils/Process.cpp
@@ -17,6 +17,7 @@
 // For starting another PrusaSlicer instance on OSX.
 // Fails to compile on Windows on the build server.
 #ifdef __APPLE__
+	#include <signal.h>
     #include <boost/process/spawn.hpp>
     #include <boost/process/args.hpp>
 #endif
@@ -78,6 +79,11 @@ static void start_new_slicer_or_gcodeviewer(const NewSlicerInstanceType instance
 			if (instance_type == NewSlicerInstanceType::Slicer && single_instance)
 				args.emplace_back("--single-instance");
 			boost::process::spawn(bin_path, args);
+			// boost::process::spawn() sets SIGINT to SIGIGN, which collides with boost::process waiting for a child to finish!
+			// https://jmmv.dev/2008/10/boostprocess-and-sigchld.html
+			// Thus reset the SIGINT to its default, so that posix waitpid() and similar continue to work.
+			// Fixes Crash on Eject in Second Instance on macOS #5507
+			signal(SIGINT, SIG_DFL);
 		}
 		catch (const std::exception& ex) {
 			BOOST_LOG_TRIVIAL(error) << "Failed to spawn a new slicer \"" << bin_path.string() << "\": " << ex.what();