diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 7a414da6b..ee123d84e 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -535,6 +535,12 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                         }
                     });
 
+                    /* On macOS, accepted sockets inherit the
+                       non-blocking flag from the server socket, so
+                       explicitly make it blocking. */
+                    if (fcntl(fdServer.get(), F_SETFL, fcntl(fdServer.get(), F_GETFL) & ~O_NONBLOCK) == -1)
+                        abort();
+
                     while (true) {
                         try {
                             auto path = readLine(fdClient.get());