diff --git a/CHANGELOG.md b/CHANGELOG.md
index d7742bd1..79decf92 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,8 @@
 All notable changes to this project will be documented in this file.
 
 ## Unreleased - ???
-- Add experimental `ffi/` module for interfacing with dynamic libraries and raw function pointers.
+- Add experimental `ffi/` module for interfacing with dynamic libraries and raw function pointers. Only available
+  on 64 bit linux, mac, and bsd systems.
 - Allow using `&named` in function prototypes for named arguments. This is a more ergonomic
   variant of `&keys` that isn't as redundant, more self documenting, and allows extension to
   things like default arguments.
diff --git a/src/include/janet.h b/src/include/janet.h
index 28d9c360..08806300 100644
--- a/src/include/janet.h
+++ b/src/include/janet.h
@@ -166,7 +166,7 @@ extern "C" {
 /* Enable or disable the FFI library. Currently, FFI only enabled on
  * x86-64, non-windows operating systems. */
 #ifndef JANET_NO_FFI
-#if !defined(JANET_WINDOWS) && (defined(__x86_64__) || defined(_M_X64))
+#if !defined(JANET_WINDOWS) && !defined(__EMSCRIPTEN__) && (defined(__x86_64__) || defined(_M_X64))
 #define JANET_FFI
 #endif
 #endif