diff --git a/3rdparty/opus/wscript b/3rdparty/opus/wscript
index 38fa0309..1b343d4d 100644
--- a/3rdparty/opus/wscript
+++ b/3rdparty/opus/wscript
@@ -3,6 +3,26 @@
 
 import os
 
+FRAGMENT_VLA='''int main (int argc, char **argv) {
+	char a[argc];
+	a[sizeof( a ) - 1] = 0;
+	int N;
+	return a[0];
+}'''
+
+FRAGMENT_ALLOCA_H='''#include <alloca.h>
+int main (void) {
+	int foo=10;
+	int * array = alloca(foo);
+}'''
+
+FRAGMENT_STDLIB_H='''#include <malloc.h>
+#include <stdlib.h>
+int main (void) {
+	int foo=10;
+	int * array = alloca(foo);
+}'''
+
 def options(opt):
 	pass
 
@@ -11,6 +31,15 @@ def configure(conf):
 		conf.fatal('Can\'t find opus submodule. Run `git submodule update --init --recursive`.')
 		return
 
+	# Check for C99 variable-size arrays, or alloca() as fallback
+	if conf.check_cc(fragment=FRAGMENT_VLA, msg = 'Checking for C99 VLA support', mandatory = False):
+		conf.define('VAR_ARRAYS', 1)
+	elif conf.check_cc(fragment=FRAGMENT_ALLOCA_H, msg = 'Checking for alloca in alloca.h header', mandatory = False):
+		conf.define('USE_ALLOCA', 1)
+		conf.define('HAVE_ALLOCA_H', 1)
+	elif conf.check_cc(fragmenmt=FRAGMENT_STDLIB_H, msg = 'Checking for alloca.h in stdlib.h', mandatory = False):
+		conf.define('USE_ALLOCA', 1)
+
 	# TODO: ARM/x86 intrinsics detection
 	# TODO: maybe call autotools/cmake/meson instead?
 
@@ -27,7 +56,7 @@ def build(bld):
 		'opus/celt/opus_custom_demo.c'
 	])
 	includes = ['opus/include/', 'opus/celt/', 'opus/silk/', 'opus/silk/float/']
-	defines = ['USE_ALLOCA', 'OPUS_BUILD', 'FLOAT_APPROX', 'PACKAGE_VERSION="1.4.0"', 'CUSTOM_MODES']
+	defines = ['OPUS_BUILD', 'FLOAT_APPROX', 'PACKAGE_VERSION="1.4.0"', 'CUSTOM_MODES']
 
 	bld.stlib(
 		source = sources,