diff --git a/src/material/schematics/ng-generate/mdc-migration/rules/tree-traversal.ts b/src/material/schematics/ng-generate/mdc-migration/rules/tree-traversal.ts
index 75105588813c..481ec8432b73 100644
--- a/src/material/schematics/ng-generate/mdc-migration/rules/tree-traversal.ts
+++ b/src/material/schematics/ng-generate/mdc-migration/rules/tree-traversal.ts
@@ -158,11 +158,6 @@ export function updateAttribute(
   const prefix = html.slice(0, index);
   const suffix = html.slice(index);
   const attrText = newValue ? `${name}="${newValue}"` : `${name}`;
-
-  if (node.startSourceSpan.start.line === node.startSourceSpan.end.line) {
-    return `${prefix} ${attrText}${suffix}`;
-  }
-
   const indentation = parseIndentation(html, node);
   return prefix + indentation + attrText + suffix;
 }
@@ -174,13 +169,13 @@ function parseIndentation(html: string, node: TmplAstElement): string {
   // Starting after the start source span's tagname,
   // read and store each char until we reach a non-whitespace char.
 
-  for (let i = startOffset; i < html.length - 1; i++) {
+  for (let i = startOffset; i < node.startSourceSpan.end.offset - 1; i++) {
     if (!/\s/.test(html.charAt(i))) {
       break;
     }
     whitespace += html.charAt(i);
   }
-  return whitespace;
+  return whitespace || ' ';
 }
 
 /**