diff --git a/bare-arm/mpconfigport.h b/bare-arm/mpconfigport.h
index 73b66802fe..1587dca57a 100644
--- a/bare-arm/mpconfigport.h
+++ b/bare-arm/mpconfigport.h
@@ -43,3 +43,5 @@ extern const struct _mp_obj_fun_native_t mp_builtin_open_obj;
 #define MICROPY_PORT_BUILTINS \
     { MP_OBJ_NEW_QSTR(MP_QSTR_open), (mp_obj_t)&mp_builtin_open_obj },
 
+// We need to provide a declaration/definition of alloca()
+#include <alloca.h>
diff --git a/qemu-arm/mpconfigport.h b/qemu-arm/mpconfigport.h
index f464712f50..e2c625ce29 100644
--- a/qemu-arm/mpconfigport.h
+++ b/qemu-arm/mpconfigport.h
@@ -33,3 +33,5 @@ extern const struct _mp_obj_fun_native_t mp_builtin_open_obj;
 #define MICROPY_PORT_BUILTINS \
     { MP_OBJ_NEW_QSTR(MP_QSTR_open), (mp_obj_t)&mp_builtin_open_obj },
 
+// We need to provide a declaration/definition of alloca()
+#include <alloca.h>
diff --git a/stmhal/mpconfigport.h b/stmhal/mpconfigport.h
index 36a60dfa7c..5b99ffca55 100644
--- a/stmhal/mpconfigport.h
+++ b/stmhal/mpconfigport.h
@@ -99,3 +99,6 @@ typedef const void *machine_const_ptr_t; // must be of pointer size
 
 // board specific definitions
 #include "mpconfigboard.h"
+
+// We need to provide a declaration/definition of alloca()
+#include <alloca.h>
diff --git a/unix-cpy/mpconfigport.h b/unix-cpy/mpconfigport.h
index 78d197033a..a4b5cc0879 100644
--- a/unix-cpy/mpconfigport.h
+++ b/unix-cpy/mpconfigport.h
@@ -48,3 +48,10 @@ typedef unsigned int machine_uint_t; // must be pointer size
 typedef void *machine_ptr_t; // must be of pointer size
 typedef const void *machine_const_ptr_t; // must be of pointer size
 typedef double machine_float_t;
+
+// We need to provide a declaration/definition of alloca()
+#ifdef __FreeBSD__
+#include <stdlib.h>
+#else
+#include <alloca.h>
+#endif
diff --git a/unix/mpconfigport.h b/unix/mpconfigport.h
index f6cef8578c..3426ae44fe 100644
--- a/unix/mpconfigport.h
+++ b/unix/mpconfigport.h
@@ -100,8 +100,7 @@ extern const struct _mp_obj_fun_native_t mp_builtin_open_obj;
     { MP_OBJ_NEW_QSTR(MP_QSTR_input), (mp_obj_t)&mp_builtin_input_obj }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_open), (mp_obj_t)&mp_builtin_open_obj },
 
-
-/* We need the correct header for alloca() */
+// We need to provide a declaration/definition of alloca()
 #ifdef __FreeBSD__
 #include <stdlib.h>
 #else
diff --git a/windows/alloca.h b/windows/alloca.h
deleted file mode 100644
index 4d47e4aabf..0000000000
--- a/windows/alloca.h
+++ /dev/null
@@ -1,29 +0,0 @@
-/*
- * This file is part of the Micro Python project, http://micropython.org/
- *
- * The MIT License (MIT)
- *
- * Copyright (c) 2013, 2014 Damien P. George
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-
-// Compatibility header to workaround lack of native alloca.h in some
-// Windows toolchains.
-#include <malloc.h>
diff --git a/windows/mpconfigport.h b/windows/mpconfigport.h
index 831a218fbc..63eeb4d962 100644
--- a/windows/mpconfigport.h
+++ b/windows/mpconfigport.h
@@ -92,7 +92,7 @@ void msec_sleep(double msec);
 #endif
 
 
-//  CL specific overrides from mpconfig
+// CL specific overrides from mpconfig
 
 #define NORETURN                   __declspec(noreturn)
 #define MICROPY_PORT_CONSTANTS     { "dummy", 0 } //can't have zero-sized array
@@ -114,7 +114,7 @@ void msec_sleep(double msec);
 
 #include <stddef.h> //for NULL
 #include <assert.h> //for assert
-#include <alloca.h> //for alloca()
+#include <malloc.h> //for alloca()
 
 // Functions implemented in platform code