diff --git a/src/core/ffi.c b/src/core/ffi.c
index 89230ab9..384e44bb 100644
--- a/src/core/ffi.c
+++ b/src/core/ffi.c
@@ -28,6 +28,10 @@
 
 #ifdef JANET_FFI
 
+#ifdef _MSC_VER
+#define alloca _alloca
+#endif
+
 typedef enum {
     JANET_FFI_TYPE_VOID,
     JANET_FFI_TYPE_SHORT,
diff --git a/src/core/util.h b/src/core/util.h
index 69d9f358..2fb597e1 100644
--- a/src/core/util.h
+++ b/src/core/util.h
@@ -32,7 +32,6 @@
 #include <stdio.h>
 #include <errno.h>
 #include <stddef.h>
-#include <alloca.h> /* for ffi */
 
 #if !defined(JANET_REDUCED_OS) || !defined(JANET_SINGLE_THREADED)
 #include <time.h>