diff --git a/projects/firefox/build.sh b/projects/firefox/build.sh
index ae71874b5..899dfe179 100755
--- a/projects/firefox/build.sh
+++ b/projects/firefox/build.sh
@@ -25,7 +25,7 @@ FUZZ_TARGETS=(
 # Firefox object (build) directory.
 OBJDIR=$WORK/obj-fuzz
 
-[[ $SANITIZER = "coverage" ]] && exit 0
+[[ $SANITIZER = "coverage" ]] && touch $OUT/empty && exit 0
 
 # Firefox fuzzing build configuration.
 cat << EOF > mozconfig