diff --git a/src/util/_impl/_bsearch_impl.scad b/src/util/_impl/_bsearch_impl.scad
new file mode 100644
index 00000000..7e1e6d79
--- /dev/null
+++ b/src/util/_impl/_bsearch_impl.scad
@@ -0,0 +1,7 @@
+use <util/_impl/_vt_default_comparator.scad>;
+
+function _binary_search(sorted, elem, low, upper) =
+    low > upper ? -1 :
+    let(mid = floor((low + upper) / 2))
+    lessThan(sorted[mid], elem) ? _binary_search(sorted, elem, mid + 1, upper) :
+    greaterThan(sorted[mid], elem) ? _binary_search(sorted, elem, low, mid - 1) : mid;
\ No newline at end of file
diff --git a/src/util/bsearch.scad b/src/util/bsearch.scad
index 68c0f436..893210bd 100644
--- a/src/util/bsearch.scad
+++ b/src/util/bsearch.scad
@@ -1,10 +1,4 @@
-use <util/_impl/_vt_default_comparator.scad>;
-
-function _binary_search(sorted, elem, low, upper) =
-    low > upper ? -1 :
-    let(mid = floor((low + upper) / 2))
-    lessThan(sorted[mid], elem) ? _binary_search(sorted, elem, mid + 1, upper) :
-    greaterThan(sorted[mid], elem) ? _binary_search(sorted, elem, low, mid - 1) : mid;
+use <util/_impl/_bsearch_impl.scad>;
 
 // for example, `sorted` is by zyx
 function bsearch(sorted, elem) = _binary_search(sorted, elem, 0, len(sorted) - 1);
\ No newline at end of file