diff --git a/src/audio_call.c b/src/audio_call.c
index 8b2ca5a..07b642f 100644
--- a/src/audio_call.c
+++ b/src/audio_call.c
@@ -41,6 +41,7 @@
 #include <stdbool.h>
 #include <curses.h>
 #include <string.h>
+#include <strings.h>
 #include <pthread.h>
 #include <unistd.h>
 #include <stdlib.h>
diff --git a/src/audio_device.c b/src/audio_device.c
index a24fc13..51e39b3 100644
--- a/src/audio_device.c
+++ b/src/audio_device.c
@@ -20,6 +20,9 @@
  *
  */
 
+/* TODO(iphydf): use nanosleep instead of usleep */
+#define _XOPEN_SOURCE 500
+
 #include "audio_device.h"
 
 #ifdef AUDIO
diff --git a/src/autocomplete.c b/src/autocomplete.c
index 45eb321..f140725 100644
--- a/src/autocomplete.c
+++ b/src/autocomplete.c
@@ -22,7 +22,9 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 #include <limits.h>
+#include <sys/param.h>
 
 #ifdef __APPLE__
 #include <sys/types.h>
diff --git a/src/chat_commands.c b/src/chat_commands.c
index 0e857f4..6a4e96d 100644
--- a/src/chat_commands.c
+++ b/src/chat_commands.c
@@ -22,6 +22,7 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 
 #include "toxic.h"
 #include "windows.h"
diff --git a/src/configdir.c b/src/configdir.c
index 8d69dc6..daef6c4 100644
--- a/src/configdir.c
+++ b/src/configdir.c
@@ -20,6 +20,7 @@
  *
  */
 
+#define _POSIX_C_SOURCE 200809L
 #include <string.h>
 #include <stdlib.h>
 #include <stdio.h>
diff --git a/src/execute.c b/src/execute.c
index 2bbf134..01998b9 100644
--- a/src/execute.c
+++ b/src/execute.c
@@ -20,6 +20,7 @@
  *
  */
 
+#define _XOPEN_SOURCE 500
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
diff --git a/src/file_transfers.h b/src/file_transfers.h
index eb7fa9f..b7b2681 100644
--- a/src/file_transfers.h
+++ b/src/file_transfers.h
@@ -24,6 +24,7 @@
 #define FILE_TRANSFERS_H
 
 #include <limits.h>
+#include <sys/param.h>
 
 #include "toxic.h"
 #include "windows.h"
diff --git a/src/global_commands.c b/src/global_commands.c
index cd9b677..c01fb18 100644
--- a/src/global_commands.c
+++ b/src/global_commands.c
@@ -22,6 +22,7 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 
 #include "toxic.h"
 #include "windows.h"
diff --git a/src/line_info.c b/src/line_info.c
index b6a414e..535f746 100644
--- a/src/line_info.c
+++ b/src/line_info.c
@@ -20,6 +20,7 @@
  *
  */
 
+#define _DEFAULT_SOURCE
 #include <stdlib.h>
 #include <string.h>
 #include <stdbool.h>
diff --git a/src/misc_tools.c b/src/misc_tools.c
index 953e863..ba316df 100644
--- a/src/misc_tools.c
+++ b/src/misc_tools.c
@@ -20,9 +20,12 @@
  *
  */
 
+#define _POSIX_C_SOURCE 200809L
+#define _XOPEN_SOURCE 500
 #include <stdlib.h>
 #include <ctype.h>
 #include <string.h>
+#include <strings.h>
 #include <time.h>
 #include <limits.h>
 #include <dirent.h>
diff --git a/src/misc_tools.h b/src/misc_tools.h
index 551f62b..8dc0686 100644
--- a/src/misc_tools.h
+++ b/src/misc_tools.h
@@ -23,6 +23,7 @@
 #define MISC_TOOLS_H
 
 #include <sys/stat.h>
+#include <sys/types.h>
 
 #include "windows.h"
 #include "toxic.h"
diff --git a/src/name_lookup.c b/src/name_lookup.c
index bed5a17..674cdf9 100644
--- a/src/name_lookup.c
+++ b/src/name_lookup.c
@@ -23,6 +23,7 @@
 #include <stdlib.h>
 #include <stdarg.h>
 #include <string.h>
+#include <strings.h>
 #include <curl/curl.h>
 
 #include "toxic.h"
diff --git a/src/settings.c b/src/settings.c
index 6490112..179b1cf 100644
--- a/src/settings.c
+++ b/src/settings.c
@@ -22,6 +22,7 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 #include <libconfig.h>
 #include <ctype.h>
 
diff --git a/src/settings.h b/src/settings.h
index b3831b6..36b11fa 100644
--- a/src/settings.h
+++ b/src/settings.h
@@ -24,6 +24,7 @@
 #define SETTINGS_H
 
 #include <limits.h>
+#include <sys/param.h>
 
 #include <tox/tox.h>
 
diff --git a/src/term_mplex.c b/src/term_mplex.c
index 1420549..5e183f4 100644
--- a/src/term_mplex.c
+++ b/src/term_mplex.c
@@ -20,6 +20,7 @@
  *
  */
 
+#define _POSIX_C_SOURCE 2
 #include <limits.h> /* PATH_MAX */
 #include <stdio.h>  /* fgets, popen, pclose */
 #include <stdlib.h> /* malloc, realloc, free, getenv */
diff --git a/src/toxic.c b/src/toxic.c
index c127f24..c0960a3 100644
--- a/src/toxic.c
+++ b/src/toxic.c
@@ -20,6 +20,7 @@
  *
  */
 
+#define _XOPEN_SOURCE 500
 #include <curses.h>
 #include <errno.h>
 #include <stdio.h>
@@ -30,6 +31,7 @@
 #include <signal.h>
 #include <locale.h>
 #include <string.h>
+#include <strings.h>
 #include <time.h>
 #include <pthread.h>
 #include <getopt.h>
diff --git a/src/video_call.c b/src/video_call.c
index d627c2e..473eafe 100644
--- a/src/video_call.c
+++ b/src/video_call.c
@@ -33,6 +33,7 @@
 #include <stdbool.h>
 #include <curses.h>
 #include <string.h>
+#include <strings.h>
 #include <pthread.h>
 #include <unistd.h>
 #include <stdlib.h>
diff --git a/src/video_device.c b/src/video_device.c
index b07cefc..44d33b7 100644
--- a/src/video_device.c
+++ b/src/video_device.c
@@ -20,6 +20,7 @@
  *
  */
 
+#define _XOPEN_SOURCE 500
 #include "video_device.h"
 #include "video_call.h"
 
diff --git a/src/xtra.c b/src/xtra.c
index f81c671..934d5a4 100644
--- a/src/xtra.c
+++ b/src/xtra.c
@@ -20,6 +20,7 @@
  *
  */
 
+#define _XOPEN_SOURCE 500
 #include "xtra.h"
 #include "misc_tools.h"