diff --git a/transpiler/src/main/java/org/jsweet/transpiler/extension/RemoveJavaDependenciesAdapter.java b/transpiler/src/main/java/org/jsweet/transpiler/extension/RemoveJavaDependenciesAdapter.java
index a0f48bb6..b42073cb 100644
--- a/transpiler/src/main/java/org/jsweet/transpiler/extension/RemoveJavaDependenciesAdapter.java
+++ b/transpiler/src/main/java/org/jsweet/transpiler/extension/RemoveJavaDependenciesAdapter.java
@@ -595,6 +595,12 @@ public class RemoveJavaDependenciesAdapter extends Java2TypeScriptAdapter {
 								.print(invocation.getTargetExpression()).print(")");
 					}
 					return true;
+				case "setCharAt":
+					printMacroName(targetMethodName);
+					print("((sb, index, c) => sb.str = sb.str.substr(0, index) + c + sb.str.substr(index + 1))(")
+							.print(invocation.getTargetExpression()).print(", ").printArgList(invocation.getArguments())
+							.print(")");
+					return true;
 				case "setLength":
 					printMacroName(targetMethodName);
 					print("((sb, length) => sb.str = sb.str.substring(0, length))(")
@@ -896,8 +902,7 @@ public class RemoveJavaDependenciesAdapter extends Java2TypeScriptAdapter {
 			if (newClass.getArgumentCount() == 0 || Util.isNumber(newClass.getArgument(0).getType())) {
 				print("{ str: \"\", toString: function() { return this.str; } }");
 			} else {
-				print("{ str: ").print(newClass.getArgument(0))
-						.print(", toString: function() { return this.str; } } }");
+				print("{ str: ").print(newClass.getArgument(0)).print(", toString: function() { return this.str; } }");
 			}
 			return true;
 		case "java.lang.ref.WeakReference":
diff --git a/transpiler/src/test/java/org/jsweet/test/transpiler/NativeStructuresTests.java b/transpiler/src/test/java/org/jsweet/test/transpiler/NativeStructuresTests.java
index 29b6e0ea..c8f4faa9 100644
--- a/transpiler/src/test/java/org/jsweet/test/transpiler/NativeStructuresTests.java
+++ b/transpiler/src/test/java/org/jsweet/test/transpiler/NativeStructuresTests.java
@@ -50,7 +50,7 @@ public class NativeStructuresTests extends AbstractTest {
 	public void testStringBuilder() {
 		eval((logHandler, result) -> {
 			Assert.assertEquals("There should be no errors", 0, logHandler.reportedProblems.size());
-			assertEquals("a,abc,a,abc,ab,X", result.get("trace"));
+			assertEquals("a,abc,a,abc,ab,X,tEst", result.get("trace"));
 		}, getSourceFile(NativeStringBuilder.class));
 	}
 
@@ -149,5 +149,6 @@ public class NativeStructuresTests extends AbstractTest {
 			assertEquals(">,0", result.get("trace"));
 		}, getSourceFile(Strings.class));
 	}
+
 	
 }
\ No newline at end of file
diff --git a/transpiler/src/test/java/source/nativestructures/NativeStringBuilder.java b/transpiler/src/test/java/source/nativestructures/NativeStringBuilder.java
index 9f3795ac..070c748d 100644
--- a/transpiler/src/test/java/source/nativestructures/NativeStringBuilder.java
+++ b/transpiler/src/test/java/source/nativestructures/NativeStringBuilder.java
@@ -40,6 +40,12 @@ public class NativeStringBuilder {
 
 		trace.push("X" + sb2.toString());
 
+		StringBuffer sb3 = new StringBuffer("test");
+
+		sb3.setCharAt(1, 'E');
+		
+		trace.push(sb3.toString());
+		
 		$export("trace", trace.join(","));
 
 	}