diff --git a/Dockerfile b/Dockerfile
index 1879b98..526ca05 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,6 @@
 FROM emscripten/emsdk:2.0.26
+# Update to tot to include EM_ASYNC_JS; remove once 2.0.27 is out:
+RUN emsdk install tot
 RUN apt-get update && apt-get install -qqy autoconf autopoint pkg-config
 WORKDIR /src
 ENV EM_CACHE /src/deps/.emcache
diff --git a/Makefile b/Makefile
index 677d00d..d89bd15 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 SYSROOT = $(EM_CACHE)/sysroot
 
-# Add custom sysroot to autoconf macro search
-# (we need this because we use custom local copy of libtool)
+# Add custom sysroot to library & macro search paths.
+export LDFLAGS += -L$(SYSROOT)/lib
 export ACLOCAL_PATH := $(SYSROOT)/share/aclocal:$(ACLOCAL_PATH)
 
 # Common linking flags for all targets.
diff --git a/deps/libusb b/deps/libusb
index 0e5f839..a08df78 160000
--- a/deps/libusb
+++ b/deps/libusb
@@ -1 +1 @@
-Subproject commit 0e5f839ebb66dcb3f428ef1f4df1ded268f7f2c9
+Subproject commit a08df78d45672e1901696c5a5b0bd73083072764