diff --git a/src/if_mzsch.c b/src/if_mzsch.c
index 0a3c201..4be3c72 100644
--- a/src/if_mzsch.c
+++ b/src/if_mzsch.c
@@ -852,7 +852,11 @@
 static void CALLBACK timer_proc(HWND, UINT, UINT, DWORD);
 static UINT timer_id = 0;
 #elif defined(FEAT_GUI_GTK)
+# if GTK_CHECK_VERSION(3,0,0)
+static gboolean timer_proc(gpointer);
+# else
 static gint timer_proc(gpointer);
+# endif
 static guint timer_id = 0;
 #elif defined(FEAT_GUI_MOTIF) || defined(FEAT_GUI_ATHENA)
 static void timer_proc(XtPointer, XtIntervalId *);
@@ -892,7 +896,11 @@
     static void CALLBACK
 timer_proc(HWND hwnd UNUSED, UINT uMsg UNUSED, UINT idEvent UNUSED, DWORD dwTime UNUSED)
 # elif defined(FEAT_GUI_GTK)
+#  if GTK_CHECK_VERSION(3,0,0)
+    static gboolean
+#  else
     static gint
+#  endif
 timer_proc(gpointer data UNUSED)
 # elif defined(FEAT_GUI_MOTIF) || defined(FEAT_GUI_ATHENA)
     static void
@@ -919,7 +927,11 @@
 # if defined(FEAT_GUI_W32)
     timer_id = SetTimer(NULL, 0, p_mzq, timer_proc);
 # elif defined(FEAT_GUI_GTK)
+#  if GTK_CHECK_VERSION(3,0,0)
+    timer_id = g_timeout_add((guint)p_mzq, (GSourceFunc)timer_proc, NULL);
+#  else
     timer_id = gtk_timeout_add((guint32)p_mzq, (GtkFunction)timer_proc, NULL);
+#  endif
 # elif defined(FEAT_GUI_MOTIF) || defined(FEAT_GUI_ATHENA)
     timer_id = XtAppAddTimeOut(app_context, p_mzq, timer_proc, NULL);
 # elif defined(FEAT_GUI_MAC)
@@ -935,7 +947,11 @@
 # if defined(FEAT_GUI_W32)
     KillTimer(NULL, timer_id);
 # elif defined(FEAT_GUI_GTK)
+#  if GTK_CHECK_VERSION(3,0,0)
+    g_source_remove(timer_id);
+#  else
     gtk_timeout_remove(timer_id);
+#  endif
 # elif defined(FEAT_GUI_MOTIF) || defined(FEAT_GUI_ATHENA)
     XtRemoveTimeOut(timer_id);
 # elif defined(FEAT_GUI_MAC)