diff --git a/src/event/SignalMonitor.cxx b/src/event/SignalMonitor.cxx
index c060d3b95..dbb0c05d0 100644
--- a/src/event/SignalMonitor.cxx
+++ b/src/event/SignalMonitor.cxx
@@ -38,13 +38,12 @@
 
 #include <algorithm>
 #include <cassert>
+#include <csignal>
 
 #ifdef USE_SIGNALFD
 #include <pthread.h>
 #endif
 
-#include <signal.h>
-
 class SignalMonitor final : private SocketMonitor {
 #ifdef USE_SIGNALFD
 	SignalFD fd;
diff --git a/src/system/FileDescriptor.hxx b/src/system/FileDescriptor.hxx
index 5fabd17dd..3faec2ce4 100644
--- a/src/system/FileDescriptor.hxx
+++ b/src/system/FileDescriptor.hxx
@@ -38,7 +38,7 @@
 #include <sys/types.h>
 
 #ifdef __linux__
-#include <signal.h>
+#include <csignal>
 #endif
 
 #ifdef _WIN32
diff --git a/src/system/SignalFD.hxx b/src/system/SignalFD.hxx
index 6c6347283..6d45d060f 100644
--- a/src/system/SignalFD.hxx
+++ b/src/system/SignalFD.hxx
@@ -32,7 +32,7 @@
 
 #include "UniqueFileDescriptor.hxx"
 
-#include <signal.h>
+#include <csignal>
 
 /**
  * A class that wraps signalfd().
diff --git a/src/unix/Daemon.cxx b/src/unix/Daemon.cxx
index d20f7d7e1..dffd4fe54 100644
--- a/src/unix/Daemon.cxx
+++ b/src/unix/Daemon.cxx
@@ -32,8 +32,8 @@
 #include <fcntl.h>
 
 #ifndef _WIN32
+#include <csignal>
 #include <sys/wait.h>
-#include <signal.h>
 #include <pwd.h>
 #include <grp.h>
 #endif
diff --git a/src/unix/SignalHandlers.cxx b/src/unix/SignalHandlers.cxx
index 5dbb47778..514b0c0be 100644
--- a/src/unix/SignalHandlers.cxx
+++ b/src/unix/SignalHandlers.cxx
@@ -28,7 +28,7 @@
 #include "system/Error.hxx"
 #include "util/Domain.hxx"
 
-#include <signal.h>
+#include <csignal>
 
 static constexpr Domain signal_handlers_domain("signal_handlers");