diff --git a/bindings/matrix-sdk-crypto-js/scripts/build.sh b/bindings/matrix-sdk-crypto-js/scripts/build.sh
index 8adb387c9..401e58851 100755
--- a/bindings/matrix-sdk-crypto-js/scripts/build.sh
+++ b/bindings/matrix-sdk-crypto-js/scripts/build.sh
@@ -21,21 +21,30 @@ RUSTFLAGS='-C opt-level=z' WASM_BINDGEN_WEAKREF=1 wasm-pack build --release --ta
 # Convert the Wasm into a JS file that exports the base64'ed Wasm.
 echo "module.exports = '$(base64 pkg/matrix_sdk_crypto_js_bg.wasm)';" > pkg/matrix_sdk_crypto_js_bg.wasm.js
 
+echo 'HEAD:';
+head -c 30 pkg/matrix_sdk_crypto_js_bg.wasm.js
+
+echo -e '\n\nTAIL:';
+tail -c 20 pkg/matrix_sdk_crypto_js_bg.wasm.js
+
 # Copy in the unbase64 module
 cp scripts/unbase64.js pkg/
 
-if test "$(uname)" = "Darwin"; then
-    SEDI="-i ''"
-else
-    SEDI="-i"
-fi
-
 # In the JavaScript:
 #  1. Replace the lines that load the Wasm,
 #  2. Remove the imports of `TextDecoder` and `TextEncoder`. We rely on the global defaults.
 loadwasm='const bytes = require("./unbase64.js")(require("./matrix_sdk_crypto_js_bg.wasm.js"));'
-sed "${SEDI}" \
-    -e "/^const path = /d" \
-    -e "s@^const bytes =.*@${loadwasm}@" \
-    -e '/Text..coder.*= require(.util.)/d' \
-    pkg/matrix_sdk_crypto_js.js
+
+if test "$(uname)" = "Darwin"; then
+    sed -i '' \
+        -e "/^const path = /d" \
+        -e "s@^const bytes =.*@${loadwasm}@" \
+        -e '/Text..coder.*= require(.util.)/d' \
+        pkg/matrix_sdk_crypto_js.js
+else
+    sed -i \
+        -e "/^const path = /d" \
+        -e "s@^const bytes =.*@${loadwasm}@" \
+        -e '/Text..coder.*= require(.util.)/d' \
+        pkg/matrix_sdk_crypto_js.js
+fi