diff --git a/ostd/range.hh b/ostd/range.hh
index 13c620f..652a91e 100644
--- a/ostd/range.hh
+++ b/ostd/range.hh
@@ -815,8 +815,18 @@ NumberRange<T> range(T v) {
 
 template<typename T>
 struct PointerRange: InputRange<PointerRange<T>, ContiguousRangeTag, T> {
+private:
+    struct Nat {};
+
+public:
     PointerRange(): p_beg(nullptr), p_end(nullptr) {}
-    PointerRange(T *beg, T *end): p_beg(beg), p_end(end) {}
+
+    template<typename U>
+    PointerRange(T *beg, U end, EnableIf<
+        (IsPointer<U>::value || IsNullPointer<U>::value) &&
+        IsConvertible<U, T *>::value, Nat
+    > = Nat()): p_beg(beg), p_end(end) {}
+
     PointerRange(T *beg, Size n): p_beg(beg), p_end(beg + n) {}
 
     template<typename U, typename = EnableIf<
diff --git a/ostd/string.hh b/ostd/string.hh
index d732caf..dbc75d4 100644
--- a/ostd/string.hh
+++ b/ostd/string.hh
@@ -29,7 +29,13 @@ private:
 
 public:
     CharRangeBase(): p_beg(nullptr), p_end(nullptr) {};
-    CharRangeBase(T *beg, T *end): p_beg(beg), p_end(end) {}
+
+    template<typename U>
+    CharRangeBase(T *beg, U end, EnableIf<
+        (IsPointer<U>::value || IsNullPointer<U>::value) &&
+        IsConvertible<U, T *>::value, Nat
+    > = Nat()): p_beg(beg), p_end(end) {}
+
     CharRangeBase(T *beg, Size n): p_beg(beg), p_end(beg + n) {}
 
     /* TODO: traits for utf-16/utf-32 string lengths, for now assume char */