diff --git a/legacy/embryo/src/bin/embryo_main.c b/legacy/embryo/src/bin/embryo_main.c
index 2cf1311a2a..0e0e0ff809 100644
--- a/legacy/embryo/src/bin/embryo_main.c
+++ b/legacy/embryo/src/bin/embryo_main.c
@@ -10,6 +10,7 @@
 #include <limits.h>
 #include <stdarg.h>
 #include <string.h>
+#include <alloca.h>
 
 /* debugging native calls */
 static int process_format_char(Embryo_Program *ep, char ch, Embryo_Cell param);