diff --git a/eng/targets/Imports.targets b/eng/targets/Imports.targets
index 4833d2849630d..f71d2f0175bd0 100644
--- a/eng/targets/Imports.targets
+++ b/eng/targets/Imports.targets
@@ -36,7 +36,7 @@
       This condition will be evaluated multiple times in multi-targeted projects hence need to be careful
       to only set in the inner builds, not the outer build where only $(TargetFrameworks) is defined.
     -->
-    <DisableNullableWarnings Condition="'$(DisableNullableWarnings)' == '' AND $(TargetFrameworks.Contains('netcoreapp3.1')) AND '$(TargetFramework)' != '' AND '$(TargetFramework)' != 'netcoreapp3.1'">true</DisableNullableWarnings>
+    <DisableNullableWarnings Condition="'$(DisableNullableWarnings)' == '' AND '$(TargetFramework)' != '' AND '$(TargetFrameworkIdentifier)' != '.NETCoreApp'">true</DisableNullableWarnings>
 
     <!--
       Disable code style analyzers in "older" targets for a multi-targeted project. These analyzers don't
diff --git a/src/Tools/BuildBoss/ProjectCheckerUtil.cs b/src/Tools/BuildBoss/ProjectCheckerUtil.cs
index 30b8b9636541b..c9a6429f2c278 100644
--- a/src/Tools/BuildBoss/ProjectCheckerUtil.cs
+++ b/src/Tools/BuildBoss/ProjectCheckerUtil.cs
@@ -274,6 +274,7 @@ private bool CheckTargetFrameworks(TextWriter textWriter)
                     case "net20":
                     case "net472":
                     case "netcoreapp3.1":
+                    case "net5.0":
                         continue;
                 }