diff --git a/utils/strings.c b/utils/strings.c
index 035a58f..aa074c1 100644
--- a/utils/strings.c
+++ b/utils/strings.c
@@ -18,6 +18,7 @@
  */
 
 #define _POSIX_C_SOURCE 200809L // for getline
+#define _GNU_SOURCE             // for getline on old systems
 
 #include <ctype.h>
 #include <stdarg.h>