diff --git a/shard.yml b/shard.yml
index 0a58fac..83c9780 100644
--- a/shard.yml
+++ b/shard.yml
@@ -1,5 +1,5 @@
 name: ipc
-version: 0.2.0
+version: 0.2.1
 
 authors:
   - Philippe Pittoli <karchnu@karchnu.fr>
diff --git a/src/high-level-bindings.cr b/src/high-level-bindings.cr
index 786fd13..58225cd 100644
--- a/src/high-level-bindings.cr
+++ b/src/high-level-bindings.cr
@@ -52,7 +52,7 @@ class IPC
   end
 
   def write(fd : Int, string : String)
-    self.write(fd, string.to_unsafe, string.size.to_u64)
+    self.write(fd, string.to_unsafe, string.bytesize.to_u64)
   end
 
   def write(fd : Int, buffer : UInt8*, buflen : UInt64)
@@ -73,7 +73,7 @@ class IPC
   end
 
   def schedule(fd : Int32, string : String)
-    self.schedule(fd, string.to_unsafe, string.size.to_u64)
+    self.schedule(fd, string.to_unsafe, string.bytesize.to_u64)
   end
 
   def schedule(fd : Int32, buffer : Array(UInt8), buflen : Int32)
diff --git a/src/message.cr b/src/message.cr
index 88ac6b7..ac6af08 100644
--- a/src/message.cr
+++ b/src/message.cr
@@ -11,7 +11,7 @@ module IPCMessage
     property payload : Bytes
 
     def initialize(string : String)
-      @payload = Bytes.new string.to_unsafe, string.size
+      @payload = Bytes.new string.to_unsafe, string.bytesize
     end
 
     def initialize(@payload)