diff --git a/legacy/embryo/src/lib/embryo_str.c b/legacy/embryo/src/lib/embryo_str.c
index 46a3284a13..8f2f5cef28 100644
--- a/legacy/embryo/src/lib/embryo_str.c
+++ b/legacy/embryo/src/lib/embryo_str.c
@@ -2,28 +2,37 @@
 # include "config.h"
 #endif
 
+#ifdef STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# ifdef HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif
+#ifdef HAVE_ALLOCA_H
+# include <alloca.h>
+#elif !defined alloca
+# ifdef __GNUC__
+#  define alloca __builtin_alloca
+# elif defined _AIX
+#  define alloca __alloca
+# elif defined _MSC_VER
+#  include <malloc.h>
+#  define alloca _alloca
+# elif !defined HAVE_ALLOCA
+#  ifdef  __cplusplus
+extern "C"
+#  endif
+void *alloca (size_t);
+# endif
+#endif
+
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 #include <fnmatch.h>
 
-#ifdef HAVE_ALLOCA_H
-# include <alloca.h>
-#elif defined __GNUC__
-# define alloca __builtin_alloca
-#elif defined _AIX
-# define alloca __alloca
-#elif defined _MSC_VER
-# include <malloc.h>
-# define alloca _alloca
-#else
-# include <stddef.h>
-# ifdef  __cplusplus
-extern "C"
-# endif
-void *alloca (size_t);
-#endif
-
 #include "Embryo.h"
 #include "embryo_private.h"