diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index ddee97372..19c851b16 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -139,12 +139,12 @@ build_wally_release_files:
     - mv release wallycore-android-jni
     - tar czf wally_dist/wallycore-android-jni.tar.gz --remove-files wallycore-android-jni
     - source /opt/emsdk/emsdk_env.sh
-    - EMCC_OPTIONS="-s EXPORT_ES6=1 -s MODULARIZE=1" tools/build_wasm.sh
+    - tools/build_wasm.sh
     - cp contrib/wally_js_example.html dist/wallycore.html
     - cd dist
     - tar czf ../wally_dist/wallycore-wasm.tar.gz --remove-files wallycore.html wallycore.js wallycore.wasm
     - cd ..
-    - EMCC_OPTIONS="-s MODULARIZE=1" EXPORTED_FUNCTIONS="['_malloc','_free','_wally_init','_wally_asset_value_commitment','_wally_asset_generator_from_bytes']" tools/build_wasm.sh
+    - EMCC_OPTIONS="-s MODULARIZE=1 -s EXPORT_NAME=InitWally" EXPORTED_FUNCTIONS="['_malloc','_free','_wally_init','_wally_asset_value_commitment','_wally_asset_generator_from_bytes']" tools/build_wasm.sh
     - cd dist
     - tar czf ../wally_dist/esplora-wasm.tar.gz --remove-files wallycore.js wallycore.wasm
     - cd ..
diff --git a/src/ccan/ccan/str/hex/hex.c b/src/ccan/ccan/str/hex/hex.c
index 522580a6d..2b9f22b45 100644
--- a/src/ccan/ccan/str/hex/hex.c
+++ b/src/ccan/ccan/str/hex/hex.c
@@ -45,9 +45,7 @@ static char hexchar(unsigned int val)
 {
 	if (val < 10)
 		return '0' + val;
-	if (val < 16)
-		return 'a' + val - 10;
-	abort();
+	return 'a' + val - 10;
 }
 
 bool hex_encode(const void *buf, size_t bufsize, char *dest, size_t destsize)
diff --git a/src/wasm_package/build.sh b/src/wasm_package/build.sh
index 787bf6f92..0dbe7cd7d 100755
--- a/src/wasm_package/build.sh
+++ b/src/wasm_package/build.sh
@@ -2,7 +2,7 @@
 set -xeo pipefail
 
 # Build WASM (Note Elements is always enabled)
-(cd ../.. && EMCC_OPTIONS="-s EXPORT_ES6=1 -s MODULARIZE=1" ./tools/build_wasm.sh)
+(cd ../.. && ./tools/build_wasm.sh)
 mkdir -p libwally_wasm && cp ../../dist/wallycore.{js,wasm} libwally_wasm/
 touch libwally_wasm/index # necessary for webpack to work (fixes "Can't resolve './' in 'wasm_package/libwally_wasm'")
 
diff --git a/tools/build_wasm.sh b/tools/build_wasm.sh
index 6acc72e9f..47164cd50 100755
--- a/tools/build_wasm.sh
+++ b/tools/build_wasm.sh
@@ -30,7 +30,7 @@ export CFLAGS="-fno-stack-protector"
 emconfigure ./configure --build=$HOST_OS ac_cv_c_bigendian=no --disable-swig-python --disable-swig-java $DISABLE_ELEMENTS --disable-tests --enable-export-all --enable-wasm-interface
 emmake make -j $num_jobs
 
-EMCC_OPTIONS="$EMCC_OPTIONS -s EXPORT_NAME=InitWally -s WASM_BIGINT"
+: ${EMCC_OPTIONS:="-s EXPORT_ES6=1 -s WASM_BIGINT"}
 : ${OPTIMIZATION_LEVEL:=3}
 : ${EXPORTED_RUNTIME_METHODS:='cwrap,ccall,getValue,UTF8ToString'}
 # Get the list of functions to export