diff --git a/lib/radisk.js b/lib/radisk.js
index fd83fddb..2075d3e8 100644
--- a/lib/radisk.js
+++ b/lib/radisk.js
@@ -189,12 +189,14 @@
 				f.sub = Radix();
 				Radix.map(rad, f.slice, {reverse: 1}); // IMPORTANT: DO THIS IN REVERSE, SO LAST HALF OF DATA MOVED TO NEW FILE BEFORE DROPPING FROM CURRENT FILE.
 				DBG && (DBG.wf2 = +new Date);
-				r.write(f.end, f.sub, f.both, o);
-				DBG && (DBG.wf3 = +new Date);
-				f.hub = Radix();
-				Radix.map(rad, f.stop);
-				DBG && (DBG.wf4 = +new Date);
-				r.write(rad.file, f.hub, f.both, o);
+				r.write(f.end, f.sub, function(err, ok){
+					if(err){ return cb(err) }
+					DBG && (DBG.wf3 = +new Date);
+					f.hub = Radix();
+					Radix.map(rad, f.stop);
+					DBG && (DBG.wf4 = +new Date);
+					r.write(rad.file, f.hub, cb, o);
+				}, o);
 				DBG && (DBG.wf5 = +new Date);
 				console.STAT && console.STAT(S, +new Date - S, "rad split", ename(rad.file), SC);
 				return true;
diff --git a/test/panic/radisk_split_failure.js b/test/panic/radisk_split_failure.js
new file mode 100644
index 00000000..b393dfd4
--- /dev/null
+++ b/test/panic/radisk_split_failure.js
@@ -0,0 +1,73 @@
+var Radisk = require('../../lib/radisk.js');
+var Radix = require('../../lib/radix.js');
+
+// Mock options
+var opt = {
+  file: 'radata_test_split_failure',
+  chunk: 10, // Very small chunk to force split
+  store: {
+    get: function (file, cb) {
+      cb(null, null);
+    },
+    put: function (file, data, cb) {
+      cb(null, 'ok');
+    },
+  },
+  log: function () {}, // Silence logs
+};
+
+var r = Radisk(opt);
+
+// Construct a radix tree that needs splitting
+// Key size + value size + overhead > 10
+// Entry: len#key:val\n
+// 3#key:val\n -> ~10 chars
+var tree = Radix();
+// Add enough keys to ensure split happens (need > 1 key)
+for (var i = 10; i < 20; i++) {
+  tree('k' + i, 'val' + i);
+}
+// tree file
+tree.file = 'root_file';
+
+console.log('--- TEST: Split Failure Safety ---');
+
+var putCalls = [];
+opt.store.put = function (file, data, cb) {
+  putCalls.push(file);
+  console.log('Store.put called for:', file);
+
+  if (file === 'root_file') {
+    // This is the old file being overwritten/truncated
+    cb(null, 'ok');
+  } else {
+    // This is the new split file
+    console.log('Simulating FAILURE for new file:', file);
+    cb('MockWriteError');
+  }
+};
+
+r.write('root_file', tree, function (err, ok) {
+  console.log('Callback received:', err);
+
+  // Check results
+  var newFileCalls = putCalls.filter(function (f) {
+    return f !== 'root_file';
+  });
+  var oldFileCalls = putCalls.filter(function (f) {
+    return f === 'root_file';
+  });
+
+  if (newFileCalls.length === 0) {
+    console.log('FAILURE: Did not attempt to write new file (Did not split?)');
+  } else if (oldFileCalls.length > 0) {
+    console.log(
+      'FAILURE: Old file was written despite new file failure! DATA LOSS RISK.',
+    );
+    console.log('Writes:', putCalls);
+  } else {
+    console.log(
+      'SUCCESS: Old file was NOT written after new file failure. Data is safe.',
+    );
+  }
+});