diff --git a/racket/src/foreign/README b/racket/src/foreign/README
index ea4635381e..7436d0e443 100644
--- a/racket/src/foreign/README
+++ b/racket/src/foreign/README
@@ -23,6 +23,8 @@ Local changes:
  * In "x86/ffi.c" for Win32, don't try to align stack for
    stdcall, fastcall, or thiscall.
 
+ * In "x86/freebsd.S", align the stack pointer to 16 bytes.
+
 ========== libffi_msvc directory =====================================
 
 This directory is synced from the CTypes repository
diff --git a/racket/src/foreign/libffi/src/x86/freebsd.S b/racket/src/foreign/libffi/src/x86/freebsd.S
index afde513164..cba17a538d 100644
--- a/racket/src/foreign/libffi/src/x86/freebsd.S
+++ b/racket/src/foreign/libffi/src/x86/freebsd.S
@@ -49,6 +49,9 @@ ffi_call_SYSV:
 	movl  16(%ebp),%ecx
 	subl  %ecx,%esp
 
+	/* Align the stack pointer to 16-bytes */
+	andl  $0xfffffff0, %esp
+
 	movl  %esp,%eax
 
 	/* Place all of the ffi_prep_args in position  */