diff --git a/generators/dart.js b/generators/dart.js
index 81b011406..f0d7715ea 100644
--- a/generators/dart.js
+++ b/generators/dart.js
@@ -173,7 +173,12 @@ Blockly.Dart.scrub_ = function(block, code) {
     // Collect comment for this block.
     var comment = block.getCommentText();
     if (comment) {
-      commentCode += Blockly.Dart.prefixLines(comment, '// ') + '\n';
+      if (block.getProcedureDef) {
+        // Use documentation comment for function comments.
+        commentCode += Blockly.Dart.prefixLines(comment + '\n', '/// ');
+      } else {
+        commentCode += Blockly.Dart.prefixLines(comment + '\n', '// ');
+      }
     }
     // Collect comments for all value arguments.
     // Don't collect comments for nested statements.
diff --git a/generators/javascript.js b/generators/javascript.js
index 5bd49f9d2..2a90b57ef 100644
--- a/generators/javascript.js
+++ b/generators/javascript.js
@@ -193,7 +193,14 @@ Blockly.JavaScript.scrub_ = function(block, code) {
     // Collect comment for this block.
     var comment = block.getCommentText();
     if (comment) {
-      commentCode += Blockly.JavaScript.prefixLines(comment, '// ') + '\n';
+      if (block.getProcedureDef) {
+        // Use a comment block for function comments.
+        commentCode += '/**\n' +
+                       Blockly.JavaScript.prefixLines(comment + '\n', ' * ') +
+                       ' */\n';
+      } else {
+        commentCode += Blockly.JavaScript.prefixLines(comment + '\n', '// ');
+      }
     }
     // Collect comments for all value arguments.
     // Don't collect comments for nested statements.
diff --git a/generators/python.js b/generators/python.js
index ddfe2f008..106812498 100644
--- a/generators/python.js
+++ b/generators/python.js
@@ -176,7 +176,12 @@ Blockly.Python.scrub_ = function(block, code) {
     // Collect comment for this block.
     var comment = block.getCommentText();
     if (comment) {
-      commentCode += Blockly.Python.prefixLines(comment, '# ') + '\n';
+      if (block.getProcedureDef) {
+        // Use a comment block for function comments.
+        commentCode += '"""' + comment + '\n"""\n';
+      } else {
+        commentCode += Blockly.Python.prefixLines(comment + '\n', '# ');
+      }
     }
     // Collect comments for all value arguments.
     // Don't collect comments for nested statements.