diff --git a/ttyplot.c b/ttyplot.c
index bb8e758..4213b78 100644
--- a/ttyplot.c
+++ b/ttyplot.c
@@ -7,9 +7,9 @@
 // Apache License 2.0
 //
 
-// This is needed on macOS to get the ncurses widechar API, and pkg-config fails to
-// define it.
-#ifdef __APPLE__
+// This is needed on FreeBSD and macOS to get the ncurses widechar API,
+// and pkg-config fails to define it.
+#if defined(__APPLE__) || defined(__FreeBSD__)
 #define _XOPEN_SOURCE_EXTENDED
 #else
 // This is needed for musl libc