diff --git a/sstables/key.cc b/sstables/key.cc
index d35f670f1f..19f3b5fbc8 100644
--- a/sstables/key.cc
+++ b/sstables/key.cc
@@ -132,8 +132,9 @@ std::vector<bytes> explode_composite(bytes_view _bytes) {
         auto b = in.read_view_to_blob<uint16_t>();
         ret.push_back(to_bytes(b));
         auto marker = in.read<uint8_t>();
-        if (marker != 0) {
-            throw runtime_exception(sprint("non-zero marker found (%d). Can't handle that yet.", marker));
+        // The components will be separated by a null byte, but the last one has special significance.
+        if (in.has_next() && (marker != 0)) {
+            throw runtime_exception(sprint("non-zero component divider found (%d) mid", marker));
         }
     }
     return ret;
diff --git a/sstables/key.hh b/sstables/key.hh
index 7397d2f25f..a99d6215b6 100644
--- a/sstables/key.hh
+++ b/sstables/key.hh
@@ -25,6 +25,19 @@ public:
     }
 };
 
+enum class composite_marker : bytes::value_type {
+    start_range = -1,
+    none = 0,
+    end_range = 1,
+};
+
+inline void check_marker(bytes_view component, composite_marker expected) {
+    auto found = composite_marker(component.back());
+    if (found != expected) {
+        throw runtime_exception(sprint("Unexpected marker. Found %d, expected %d\n", uint8_t(found), uint8_t(expected)));
+    }
+}
+
 // Our internal representation differs slightly (in the way it serializes) from Origin.
 // In order to be able to achieve read and write compatibility for sstables - so they can
 // be imported and exported - we need to always convert a key to this representation.
@@ -57,6 +70,7 @@ public:
     composite_view(bytes_view b) : _bytes(b) {}
 
     std::vector<bytes> explode() const;
+
     explicit operator bytes_view() const {
         return _bytes;
     }