diff --git a/testing/symbols/pubspec.yaml b/testing/symbols/pubspec.yaml
index 57ea17a265afe..6f78767c10912 100644
--- a/testing/symbols/pubspec.yaml
+++ b/testing/symbols/pubspec.yaml
@@ -5,7 +5,7 @@
 name: verify_exported
 publish_to: none
 environment:
-  sdk: '>=2.11.0 <3.0.0'
+  sdk: '>=2.12.0 <3.0.0'
 
 # Do not add any dependencies that require more than what is provided in
 # //third_party/pkg, //third_party/dart/pkg, or
diff --git a/testing/symbols/verify_exported.dart b/testing/symbols/verify_exported.dart
index 83a1d6d1785e3..809505aeae7f2 100644
--- a/testing/symbols/verify_exported.dart
+++ b/testing/symbols/verify_exported.dart
@@ -221,7 +221,7 @@ int _checkAndroid(String outPath, String nmPath, Iterable<String> builds) {
     final Map<String, String> badSymbols = <String, String>{};
     for (final String key in entryMap.keys) {
       if (entryMap[key] != expectedSymbols[key]) {
-        badSymbols[key] = entryMap[key];
+        badSymbols[key] = entryMap[key]!;
       }
     }
     if (badSymbols.isNotEmpty) {