diff --git a/buffer/buffer.mbt b/buffer/buffer.mbt
index 57a43eba1..9fc6c9e3c 100644
--- a/buffer/buffer.mbt
+++ b/buffer/buffer.mbt
@@ -80,7 +80,7 @@ pub fn write_bytes(self : Buffer, value : Bytes) -> Unit {
 }
 
 /// Write a sub-string into buffer.
-pub fn write_sub_string(
+pub fn write_substring(
   self : Buffer,
   value : String,
   start : Int,
@@ -92,6 +92,17 @@ pub fn write_sub_string(
   self.len += len * 2
 }
 
+/// Write a sub-string into buffer.
+/// @alert deprecated "Use `Buffer::write_substring` instead"
+pub fn write_sub_string(
+  self : Buffer,
+  value : String,
+  start : Int,
+  len : Int
+) -> Unit {
+  self.write_substring(value, start, len)
+}
+
 /// Write a char into buffer.
 pub fn write_char(self : Buffer, value : Char) -> Unit {
   self.grow_if_necessary(self.len + 4)
diff --git a/buffer/buffer.mbti b/buffer/buffer.mbti
index 4aced83e0..cdc4299df 100644
--- a/buffer/buffer.mbti
+++ b/buffer/buffer.mbti
@@ -14,7 +14,8 @@ impl Buffer {
   write_char(Self, Char) -> Unit
   write_object(Self, Show) -> Unit
   write_string(Self, String) -> Unit
-  write_sub_string(Self, String, Int, Int) -> Unit
+  write_sub_string(Self, String, Int, Int) -> Unit //deprecated
+  write_substring(Self, String, Int, Int) -> Unit
 }
 
 // Type aliases
diff --git a/buffer/buffer_test.mbt b/buffer/buffer_test.mbt
index a1365f707..ca781207b 100644
--- a/buffer/buffer_test.mbt
+++ b/buffer/buffer_test.mbt
@@ -32,9 +32,9 @@ test "grow_if_necessary method" {
   assert_true!(buf.to_bytes().length() >= 60)
 }
 
-test "write_sub_string method" {
+test "write_substring method" {
   let buf = @buffer.new(size_hint=10)
-  buf.write_sub_string("Hello, World!", 7, 5)
+  buf.write_substring("Hello, World!", 7, 5)
   inspect!(buf, content="World")
 }
 
@@ -66,9 +66,9 @@ test "grow_if_necessary method" {
   assert_true!(buf.to_bytes().length() >= 60)
 }
 
-test "write_sub_string method" {
+test "write_substring method" {
   let buf = @buffer.new(size_hint=10)
-  buf.write_sub_string("Hello, World!", 7, 5)
+  buf.write_substring("Hello, World!", 7, 5)
   inspect!(buf, content="World")
 }
 
@@ -106,9 +106,9 @@ test "grow_if_necessary method" {
   assert_true!(buf.to_bytes().length() >= 60)
 }
 
-test "write_sub_string method" {
+test "write_substring method" {
   let buf = @buffer.new(size_hint=10)
-  buf.write_sub_string("Hello, World!", 7, 5)
+  buf.write_substring("Hello, World!", 7, 5)
   inspect!(buf, content="World")
 }
 
diff --git a/builtin/buffer.mbt b/builtin/buffer.mbt
index a32861102..a4f937957 100644
--- a/builtin/buffer.mbt
+++ b/builtin/buffer.mbt
@@ -81,7 +81,7 @@ pub fn write_bytes(self : Buffer, value : Bytes) -> Unit {
 }
 
 /// Write a sub-string into buffer.
-pub fn write_sub_string(
+pub fn write_substring(
   self : Buffer,
   value : String,
   start : Int,
@@ -93,6 +93,17 @@ pub fn write_sub_string(
   self.len += len * 2
 }
 
+/// Write a sub-string into buffer.
+/// @alert deprecated "Use `Buffer::write_substring` instead"
+pub fn write_sub_string(
+  self : Buffer,
+  value : String,
+  start : Int,
+  len : Int
+) -> Unit {
+  self.write_substring(value, start, len)
+}
+
 /// Write a char into buffer.
 pub fn write_char(self : Buffer, value : Char) -> Unit {
   self.grow_if_necessary(self.len + 4)
diff --git a/builtin/builtin.mbti b/builtin/builtin.mbti
index 6da03d1a7..54fd2a5b5 100644
--- a/builtin/builtin.mbti
+++ b/builtin/builtin.mbti
@@ -175,7 +175,8 @@ impl Buffer {
   write_char(Self, Char) -> Unit
   write_object(Self, Show) -> Unit
   write_string(Self, String) -> Unit
-  write_sub_string(Self, String, Int, Int) -> Unit
+  write_sub_string(Self, String, Int, Int) -> Unit //deprecated
+  write_substring(Self, String, Int, Int) -> Unit
 }
 
 pub type! Failure String
@@ -350,7 +351,7 @@ impl StringBuilder {
   write_char(Self, Char) -> Unit
   write_object[T : Show](Self, T) -> Unit
   write_string(Self, String) -> Unit
-  write_sub_string(Self, String, Int, Int) -> Unit
+  write_substring(Self, String, Int, Int) -> Unit
 }
 
 pub type UnsafeMaybeUninit
@@ -723,6 +724,7 @@ pub trait Hash {
 
 pub trait Logger {
   write_string(Self, String) -> Unit
+  write_substring(Self, String, Int, Int) -> Unit
   write_sub_string(Self, String, Int, Int) -> Unit
   write_char(Self, Char) -> Unit
 }
@@ -765,6 +767,8 @@ impl Hash for Tuple(6)
 
 impl Hash for Tuple(7)
 
+impl Logger::write_sub_string
+
 impl Show for Unit
 
 impl Show for Bool
diff --git a/builtin/show.mbt b/builtin/show.mbt
index 3693ed990..feb6ca8e9 100644
--- a/builtin/show.mbt
+++ b/builtin/show.mbt
@@ -70,7 +70,7 @@ pub impl Show for String with output(self, logger) {
   let mut segment_start = 0
   fn flush_segment(i : Int) {
     if i > segment_start {
-      logger.write_sub_string(self, segment_start, i - segment_start)
+      logger.write_substring(self, segment_start, i - segment_start)
     }
     segment_start = i + 1
   }
diff --git a/builtin/stringbuilder_buffer.mbt b/builtin/stringbuilder_buffer.mbt
index b7c5f13e8..a6df1876b 100644
--- a/builtin/stringbuilder_buffer.mbt
+++ b/builtin/stringbuilder_buffer.mbt
@@ -53,7 +53,7 @@ pub fn StringBuilder::write_char(self : StringBuilder, ch : Char) -> Unit {
   self.len += inc
 }
 
-pub fn StringBuilder::write_sub_string(
+pub fn StringBuilder::write_substring(
   self : StringBuilder,
   str : String,
   start : Int,
diff --git a/builtin/stringbuilder_concat.mbt b/builtin/stringbuilder_concat.mbt
index dad240989..963fe795c 100644
--- a/builtin/stringbuilder_concat.mbt
+++ b/builtin/stringbuilder_concat.mbt
@@ -27,7 +27,7 @@ pub fn StringBuilder::write_char(self : StringBuilder, ch : Char) -> Unit {
   self.val += Char::to_string(ch)
 }
 
-pub fn StringBuilder::write_sub_string(
+pub fn StringBuilder::write_substring(
   self : StringBuilder,
   str : String,
   start : Int,
diff --git a/builtin/stringbuilder_test.mbt b/builtin/stringbuilder_test.mbt
index 5d4eb3749..14ee350bd 100644
--- a/builtin/stringbuilder_test.mbt
+++ b/builtin/stringbuilder_test.mbt
@@ -24,7 +24,7 @@ test "stringbuilder" {
   let buf = StringBuilder::new()
   buf.write_string("hello")
   buf.write_char(' ')
-  buf.write_sub_string("world", 0, 3)
+  buf.write_substring("world", 0, 3)
   inspect!(buf.to_string(), content="hello wor")
 }
 
diff --git a/builtin/traits.mbt b/builtin/traits.mbt
index a7903494a..93f6ac852 100644
--- a/builtin/traits.mbt
+++ b/builtin/traits.mbt
@@ -47,10 +47,16 @@ pub trait Default {
 /// Trait for a logger, where debug logs can be written into
 pub trait Logger {
   write_string(Self, String) -> Unit
+  write_substring(Self, String, Int, Int) -> Unit
+  /// @alert deprecated "use `Logger::write_substring` instead"
   write_sub_string(Self, String, Int, Int) -> Unit
   write_char(Self, Char) -> Unit
 }
 
+impl Logger with write_sub_string(self, value, start, len) {
+  self.write_substring(value, start, len)
+}
+
 /// Trait for types that can be converted to `String`
 pub trait Show {
   // `output` is used for composition of aggregate structure.
diff --git a/coverage/coverage.mbt b/coverage/coverage.mbt
index a0c414ee4..21169c901 100644
--- a/coverage/coverage.mbt
+++ b/coverage/coverage.mbt
@@ -102,14 +102,14 @@ pub fn end() -> Unit {
     let mut start = 0
     for j = 0; j < str.length(); j = j + 1 {
       if str[j] == '\n' {
-        line_buf.write_sub_string(str, start, j)
+        line_buf.write_substring(str, start, j)
         println(line_buf.to_string())
         line_buf.reset()
         start = j + 1
       }
     }
     if start < str.length() {
-      line_buf.write_sub_string(str, start, str.length())
+      line_buf.write_substring(str, start, str.length())
     }
   }
   let trailing_line = line_buf.to_string()
diff --git a/json/lex_string.mbt b/json/lex_string.mbt
index a0aea994e..455b5e5f2 100644
--- a/json/lex_string.mbt
+++ b/json/lex_string.mbt
@@ -17,7 +17,7 @@ fn lex_string(ctx : ParseContext) -> String!ParseError {
   let mut start = ctx.offset
   fn flush(end : Int) {
     if start > 0 && end > start {
-      buf.write_sub_string(ctx.input, start, end - start)
+      buf.write_substring(ctx.input, start, end - start)
     }
   }