diff --git a/otto.sh b/otto.sh
index 235bb4b..8c8de3f 100755
--- a/otto.sh
+++ b/otto.sh
@@ -38,8 +38,8 @@ add_module_to_cmakes () {
 remove_module_from_cmakes () {
     local basename="$1"
 
-    sed "s/^.*add_subdirectory(${basename}).*$//g" ./src/CMakeLists.txt > ./src/CMakeLists.txt
-    sed "s/^.*add_subdirectory(${basename}).*$//g" ./tests/CMakeLists.txt > ./tests/CMakeLists.txt
+    sed -i'' "s/^.*add_subdirectory(${basename}).*$//g" ./src/CMakeLists.txt 
+    sed -i'' "s/^.*add_subdirectory(${basename}).*$//g" ./tests/CMakeLists.txt 
 }
 
 git_add_module () {