diff --git a/modules/webm/libvpx/SCsub b/modules/webm/libvpx/SCsub
index c681e2b34fb..2daf8c282f7 100644
--- a/modules/webm/libvpx/SCsub
+++ b/modules/webm/libvpx/SCsub
@@ -38,7 +38,6 @@ libvpx_sources = [
     "vp8/decoder/decodemv.c",
     "vp8/decoder/detokenize.c",
     "vp8/decoder/onyxd_if.c",
-    "vp8/decoder/threading.c",
 
 
     "vp9/vp9_dx_iface.c",
@@ -102,6 +101,10 @@ libvpx_sources = [
     "vpx_util/vpx_thread.c"
 ]
 
+libvpx_sources_mt = [
+    "vp8/decoder/threading.c",
+]
+
 libvpx_sources_intrin_x86 = [
     "vp8/common/x86/filter_x86.c",
     "vp8/common/x86/loopfilter_x86.c",
@@ -231,6 +234,7 @@ libvpx_sources_arm_neon_gas_apple = [
 ]
 
 libvpx_sources = [libvpx_dir + file for file in libvpx_sources]
+libvpx_sources_mt = [libvpx_dir + file for file in libvpx_sources_mt]
 libvpx_sources_intrin_x86 = [libvpx_dir + file for file in libvpx_sources_intrin_x86]
 libvpx_sources_intrin_x86_mmx = [libvpx_dir + file for file in libvpx_sources_intrin_x86_mmx]
 libvpx_sources_intrin_x86_sse2 = [libvpx_dir + file for file in libvpx_sources_intrin_x86_sse2]
@@ -253,6 +257,8 @@ env_webm.Append(CPPPATH=[libvpx_dir])
 env_libvpx = env.Clone()
 env_libvpx.Append(CPPPATH=[libvpx_dir])
 
+webm_multithread = env["platform"] != 'javascript'
+
 cpu_bits = env["bits"]
 webm_cpu_x86 = False
 webm_cpu_arm = False
@@ -338,6 +344,10 @@ if webm_simd_optimizations == False:
     print("WebM SIMD optimizations are disabled. Check if your CPU architecture, CPU bits or platform are supported!")
 
 env_libvpx.add_source_files(env.modules_sources, libvpx_sources)
+
+if webm_multithread:
+    env_libvpx.add_source_files(env.modules_sources, libvpx_sources_mt)
+
 if webm_cpu_x86:
     is_clang_or_gcc = ('gcc' in env["CC"]) or ('clang' in env["CC"]) or ("OSXCROSS_ROOT" in os.environ)
 
diff --git a/platform/javascript/detect.py b/platform/javascript/detect.py
index fc909f66192..17b31f8d739 100644
--- a/platform/javascript/detect.py
+++ b/platform/javascript/detect.py
@@ -25,7 +25,6 @@ def get_opts():
 def get_flags():
     return [
         ('tools', False),
-        ('module_theora_enabled', False),
         # Disabling the mbedtls module reduces file size.
         # The module has little use due to the limited networking functionality
         # in this platform. For the available networking methods, the browser
diff --git a/thirdparty/libvpx/vpx_config.h b/thirdparty/libvpx/vpx_config.h
index fb9e13c4ada..6caec50c81a 100644
--- a/thirdparty/libvpx/vpx_config.h
+++ b/thirdparty/libvpx/vpx_config.h
@@ -67,6 +67,12 @@
 
 #define CONFIG_BIG_ENDIAN 0 //TODO: Autodetect
 
+#ifdef __EMSCRIPTEN__
+#define CONFIG_MULTITHREAD 0
+#else
+#define CONFIG_MULTITHREAD 1
+#endif
+
 #ifdef _WIN32
 	#define HAVE_PTHREAD_H 0
 	#define HAVE_UNISTD_H 0
@@ -95,7 +101,6 @@
 #define CONFIG_RUNTIME_CPU_DETECT 1
 #define CONFIG_POSTPROC 0
 #define CONFIG_VP9_POSTPROC 0
-#define CONFIG_MULTITHREAD 1
 #define CONFIG_INTERNAL_STATS 0
 #define CONFIG_VP8_ENCODER 0
 #define CONFIG_VP8_DECODER 1