diff --git a/CHANGELOG.md b/CHANGELOG.md
index 565c48d6..ae5181a6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,7 @@
 ## 1.22.11
 
+* Don't try to load unquoted plain-CSS indented-syntax imports.
+
 * Fix a couple edge cases in `@extend` logic and related selector functions:
 
   * Recognize `:matches()` and similar pseudo-selectors as superselectors of
diff --git a/lib/src/parse/sass.dart b/lib/src/parse/sass.dart
index fe5aebbe..eb39aa26 100644
--- a/lib/src/parse/sass.dart
+++ b/lib/src/parse/sass.dart
@@ -9,6 +9,7 @@ import '../ast/sass.dart';
 import '../interpolation_buffer.dart';
 import '../logger.dart';
 import '../util/character.dart';
+import '../value.dart';
 import 'stylesheet.dart';
 
 /// A parser for the indented syntax.
@@ -98,9 +99,21 @@ class SassParser extends StylesheetParser {
       scanner.readChar();
       next = scanner.peekChar();
     }
+    var url = scanner.substring(start.position);
+    var span = scanner.spanFrom(start);
 
-    return DynamicImport(parseImportUrl(scanner.substring(start.position)),
-        scanner.spanFrom(start));
+    if (isPlainImportUrl(url)) {
+      // Serialize [url] as a Sass string because [StaticImport] expects it to
+      // include quotes.
+      return StaticImport(
+          Interpolation([SassString(url).toString()], span), span);
+    } else {
+      try {
+        return DynamicImport(parseImportUrl(url), span);
+      } on FormatException catch (innerError) {
+        error("Invalid URL: ${innerError.message}", span);
+      }
+    }
   }
 
   bool scanElse(int ifIndentation) {
diff --git a/lib/src/parse/stylesheet.dart b/lib/src/parse/stylesheet.dart
index 0bcde8c7..e25e5ac2 100644
--- a/lib/src/parse/stylesheet.dart
+++ b/lib/src/parse/stylesheet.dart
@@ -1002,7 +1002,7 @@ abstract class StylesheetParser extends Parser {
     var urlSpan = scanner.spanFrom(start);
     whitespace();
     var queries = tryImportQueries();
-    if (_isPlainImportUrl(url) || queries != null) {
+    if (isPlainImportUrl(url) || queries != null) {
       return StaticImport(
           Interpolation([urlSpan.text], urlSpan), scanner.spanFrom(start),
           supports: queries?.item1, media: queries?.item2);
@@ -1028,7 +1028,8 @@ abstract class StylesheetParser extends Parser {
   }
 
   /// Returns whether [url] indicates that an `@import` is a plain CSS import.
-  bool _isPlainImportUrl(String url) {
+  @protected
+  bool isPlainImportUrl(String url) {
     if (url.length < 5) return false;
     if (url.endsWith(".css")) return true;