diff --git a/src/common/backtrace.c b/src/common/backtrace.c
index 8b76720bf..fb6ff71a1 100644
--- a/src/common/backtrace.c
+++ b/src/common/backtrace.c
@@ -28,7 +28,11 @@
 #include <stdio.h>
 #include <string.h>
 #include <stdarg.h>
+
+#ifndef __USE_GNU
 #define __USE_GNU
+#endif
+
 #include <dlfcn.h>
 
 #ifdef HAVE_BACKTRACE
diff --git a/src/common/utf8.c b/src/common/utf8.c
index 9379082e4..d1cfbd927 100644
--- a/src/common/utf8.c
+++ b/src/common/utf8.c
@@ -26,7 +26,10 @@
 
 #include <stdlib.h>
 #include <string.h>
+
+#ifndef __USE_XOPEN
 #define __USE_XOPEN
+#endif
 
 #if defined(__OpenBSD__)
 #include <utf8/wchar.h>
diff --git a/weechat/src/common/backtrace.c b/weechat/src/common/backtrace.c
index 8b76720bf..fb6ff71a1 100644
--- a/weechat/src/common/backtrace.c
+++ b/weechat/src/common/backtrace.c
@@ -28,7 +28,11 @@
 #include <stdio.h>
 #include <string.h>
 #include <stdarg.h>
+
+#ifndef __USE_GNU
 #define __USE_GNU
+#endif
+
 #include <dlfcn.h>
 
 #ifdef HAVE_BACKTRACE
diff --git a/weechat/src/common/utf8.c b/weechat/src/common/utf8.c
index 9379082e4..d1cfbd927 100644
--- a/weechat/src/common/utf8.c
+++ b/weechat/src/common/utf8.c
@@ -26,7 +26,10 @@
 
 #include <stdlib.h>
 #include <string.h>
+
+#ifndef __USE_XOPEN
 #define __USE_XOPEN
+#endif
 
 #if defined(__OpenBSD__)
 #include <utf8/wchar.h>