diff --git a/src/core/features.h b/src/core/features.h
index a7dcedd5..e74f09d2 100644
--- a/src/core/features.h
+++ b/src/core/features.h
@@ -25,12 +25,6 @@
 #ifndef JANET_FEATURES_H_defined
 #define JANET_FEATURES_H_defined
 
-#if !defined(_POSIX_C_SOURCE)
 #define _POSIX_C_SOURCE 200112L
-#endif
-
-#if !defined(_BSD_SOURCE) && defined(JANET_BSD)
-#define _BSD_SOURCE 1
-#endif
 
 #endif
diff --git a/src/mainclient/line.h b/src/mainclient/line.h
index 8b312f10..eced3d13 100644
--- a/src/mainclient/line.h
+++ b/src/mainclient/line.h
@@ -23,6 +23,10 @@
 #ifndef JANET_LINE_H_defined
 #define JANET_LINE_H_defined
 
+#if !defined(_POSIX_C_SOURCE)
+#define _POSIX_C_SOURCE 200112L
+#endif
+
 #ifndef JANET_AMALG
 #include <janet.h>
 #endif
diff --git a/src/mainclient/main.c b/src/mainclient/main.c
index dcc9f6b6..8883fb90 100644
--- a/src/mainclient/main.c
+++ b/src/mainclient/main.c
@@ -20,6 +20,10 @@
 * IN THE SOFTWARE.
 */
 
+#if !defined(_POSIX_C_SOURCE)
+#define _POSIX_C_SOURCE 200112L
+#endif
+
 #ifndef JANET_AMALG
 #include <janet.h>
 #include "line.h"