diff --git a/projects/spidermonkey-ufi/build.sh b/projects/spidermonkey-ufi/build.sh
index 7356ff6cc..0460c0e43 100755
--- a/projects/spidermonkey-ufi/build.sh
+++ b/projects/spidermonkey-ufi/build.sh
@@ -38,8 +38,8 @@ mkdir -p build_OPT.OBJ
 cd build_OPT.OBJ
 
 ../configure \
-    --enable-optimize \
-    --disable-shared-js \
+    --enable-debug \
+    --enable-optimize="-O2 -gline-tables-only" \
     --disable-jemalloc \
     --enable-tests \
     --enable-fuzzing \
diff --git a/projects/spidermonkey/build.sh b/projects/spidermonkey/build.sh
index 8be21765b..042a741fc 100755
--- a/projects/spidermonkey/build.sh
+++ b/projects/spidermonkey/build.sh
@@ -30,8 +30,7 @@ cd build_DBG.OBJ
 # Temporarily disable cranelift (see bug 1497570)
 ../configure \
     --enable-debug \
-    --enable-optimize \
-    --disable-shared-js \
+    --enable-optimize="-O2 -gline-tables-only" \
     --disable-jemalloc \
     --disable-tests \
     --enable-address-sanitizer \