diff --git a/ext/json/generator/simd.h b/ext/json/generator/simd.h
index 4deb97b4de..2fbc93169d 100644
--- a/ext/json/generator/simd.h
+++ b/ext/json/generator/simd.h
@@ -1,5 +1,3 @@
-#include "extconf.h"
-
 typedef enum {
     SIMD_NONE,
     SIMD_NEON,