https://gitlab.com/embeddable-common-lisp/ecl/-/merge_requests/301

diff --git src/c/main.d src/c/main.d
index fbaae6674..532320792 100644
--- src/c/main.d
+++ src/c/main.d
@@ -46,6 +46,10 @@
 #include "ecl_features.h"
 #include "iso_latin_names.h"
 
+#if defined(__APPLE__) && defined(HAVE_ENVIRON)
+# include <crt_externs.h>
+#endif
+
 /******************************* EXPORTS ******************************/
 
 #if !defined(ECL_THREADS)
@@ -899,7 +903,12 @@ si_environ(void)
   cl_object output = ECL_NIL;
 #ifdef HAVE_ENVIRON
   char **p;
+/* Shared libraries do not have direct access to environ on Darwin */
+#if defined(__APPLE__)
+# define environ (*_NSGetEnviron())
+#elif !defined(environ)
   extern char **environ;
+#endif
   for (p = environ; *p; p++) {
     output = CONS(ecl_make_constant_base_string(*p,-1), output);
   }