diff --git a/src/core/session_consolekit.cpp b/src/core/session_consolekit.cpp
index 0200407e63d7cefffb6ab8f34a4c6f26846ac00a..c0e8449f8a2a47e3e54475fccb50f573346e0ede 100644
--- a/src/core/session_consolekit.cpp
+++ b/src/core/session_consolekit.cpp
@@ -239,7 +239,7 @@ FileDescriptor ConsoleKitSession::delaySleep(const QString &reason)
         return FileDescriptor{};
     }
     const QDBusUnixFileDescriptor descriptor = reply.arguments().constFirst().value<QDBusUnixFileDescriptor>();
-    return FileDescriptor{descriptor.fileDescriptor()};
+    return FileDescriptor{fcntl(descriptor.fileDescriptor(), F_DUPFD_CLOEXEC, 0)};
 }
 
 ConsoleKitSession::ConsoleKitSession(const QString &sessionPath)
diff --git a/src/core/session_logind.cpp b/src/core/session_logind.cpp
index 978c410cfeae8b91336f035b99ae11764faec498..5f6541c289b5fa263a3534821ec9c3b33490005b 100644
--- a/src/core/session_logind.cpp
+++ b/src/core/session_logind.cpp
@@ -237,7 +237,7 @@ FileDescriptor LogindSession::delaySleep(const QString &reason)
         return FileDescriptor{};
     }
     const QDBusUnixFileDescriptor descriptor = reply.arguments().constFirst().value<QDBusUnixFileDescriptor>();
-    return FileDescriptor{descriptor.fileDescriptor()};
+    return FileDescriptor(fcntl(descriptor.fileDescriptor(), F_DUPFD_CLOEXEC, 0));
 }
 
 LogindSession::LogindSession(const QString &sessionPath)
diff --git a/src/utils/filedescriptor.cpp b/src/utils/filedescriptor.cpp
index d60c429e446c041a46d8c91adca20eba316fa71c..f76f07aad1ac227a96ef307c4cdab783414648fe 100644
--- a/src/utils/filedescriptor.cpp
+++ b/src/utils/filedescriptor.cpp
@@ -7,6 +7,7 @@
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 #include "filedescriptor.h"
+#include "common.h"
 
 #include <fcntl.h>
 #include <sys/poll.h>
@@ -29,7 +30,12 @@ FileDescriptor::FileDescriptor(FileDescriptor &&other)
 FileDescriptor &FileDescriptor::operator=(FileDescriptor &&other)
 {
     if (m_fd != -1) {
-        ::close(m_fd);
+        const int err = ::close(m_fd);
+        if (Q_UNLIKELY(err != 0)) {
+            // If this failed, we've either closed the fd somewhere else, or we end up
+            // leaking this fd here. Either way, there's some significant bug!
+            qCCritical(KWIN_CORE, "::close() failed: %s", strerror(errno));
+        }
     }
     m_fd = std::exchange(other.m_fd, -1);
     return *this;
@@ -38,7 +44,12 @@ FileDescriptor &FileDescriptor::operator=(FileDescriptor &&other)
 FileDescriptor::~FileDescriptor()
 {
     if (m_fd != -1) {
-        ::close(m_fd);
+        const int err = ::close(m_fd);
+        if (Q_UNLIKELY(err != 0)) {
+            // If this failed, we've either closed the fd somewhere else, or we end up
+            // leaking this fd here. Either way, there's some significant bug!
+            qCCritical(KWIN_CORE, "::close() failed: %s", strerror(errno));
+        }
     }
 }
 
@@ -60,7 +71,12 @@ int FileDescriptor::take()
 void FileDescriptor::reset()
 {
     if (m_fd != -1) {
-        ::close(m_fd);
+        const int err = ::close(m_fd);
+        if (Q_UNLIKELY(err != 0)) {
+            // If this failed, we've either closed the fd somewhere else, or we end up
+            // leaking this fd here. Either way, there's some significant bug!
+            qCCritical(KWIN_CORE, "::close() failed: %s", strerror(errno));
+        }
         m_fd = -1;
     }
 }