diff --git a/src/c/main.d b/src/c/main.d
index 6a0d1aed4..7e922d8df 100644
--- a/src/c/main.d
+++ b/src/c/main.d
@@ -75,8 +75,8 @@ static cl_fixnum option_values[ECL_OPT_LIMIT+1] = {
 	128,		/* ECL_OPT_FRAME_STACK_SAFETY_AREA */
 	32768,		/* ECL_OPT_LISP_STACK_SIZE */
 	128,		/* ECL_OPT_LISP_STACK_SAFETY_AREA */
-	4*1024*1024,	/* ECL_OPT_C_STACK_SIZE */
-	128*1024,	/* ECL_OPT_C_STACK_SAFETY_AREA */
+	512*1024,	/* ECL_OPT_C_STACK_SIZE */
+	16*1024,	/* ECL_OPT_C_STACK_SAFETY_AREA */
 	1,		/* ECL_OPT_SIGALTSTACK_SIZE */
 	256*1024*1024, 	/* ECL_OPT_HEAP_SIZE */
 	1024*1024, 	/* ECL_OPT_HEAP_SAFETY_AREA */