diff --git a/lib/src/lib.c b/lib/src/lib.c
index 49ddf672..9926ae0b 100644
--- a/lib/src/lib.c
+++ b/lib/src/lib.c
@@ -5,6 +5,7 @@
 //   - include
 //   - externals/utf8proc
 
+#define _POSIX_SOURCE
 #include "./get_changed_ranges.c"
 #include "./language.c"
 #include "./lexer.c"