diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cb64f70bcd..6ebaa71fb8 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -30,7 +30,7 @@ jobs:
         run: |
           sudo apt-get install lua5.1
           make check-scripts
-          make test
+          make TREAT_WARNINGS_AS_ERRORS=true test
 
   linux-mono:
     name: Linux (mono)
@@ -48,7 +48,7 @@ jobs:
       - name: Check Mods
         run: |
           # check-scripts does not depend on .net/mono, so is not needed here
-          make RUNTIME=mono test
+          make RUNTIME=mono TREAT_WARNINGS_AS_ERRORS=true test
 
   windows:
     name: Windows (.NET 6.0)
@@ -76,5 +76,6 @@ jobs:
         run: |
           chocolatey install lua --version 5.1.5.52
           $ENV:Path = $ENV:Path + ";C:\Program Files (x86)\Lua\5.1\"
+          $ENV:TREAT_WARNINGS_AS_ERRORS = "true"
           .\make.ps1 check-scripts
           .\make.ps1 test
diff --git a/Makefile b/Makefile
index 7e8ceea556..903b7f6992 100644
--- a/Makefile
+++ b/Makefile
@@ -180,7 +180,7 @@ help:
 	@echo '  make [RUNTIME=net6] TARGETPLATFORM=unix-generic'
 	@echo
 	@echo 'to check the official mods for erroneous yaml files, run:'
-	@echo '  make [RUNTIME=net6] test'
+	@echo '  make [RUNTIME=net6] [TREAT_WARNINGS_AS_ERRORS=false] test'
 	@echo
 	@echo 'to check the engine and official mod dlls for code style violations, run:'
 	@echo '  make [RUNTIME=net6] check'
diff --git a/OpenRA.Mods.Common/UtilityCommands/CheckYaml.cs b/OpenRA.Mods.Common/UtilityCommands/CheckYaml.cs
index ad1eacc909..267827235a 100644
--- a/OpenRA.Mods.Common/UtilityCommands/CheckYaml.cs
+++ b/OpenRA.Mods.Common/UtilityCommands/CheckYaml.cs
@@ -41,11 +41,14 @@ namespace OpenRA.Mods.Common.UtilityCommands
 			return true;
 		}
 
+		bool warningAsError = false;
+
 		[Desc("[MAPFILE]", "Check a mod or map for certain yaml errors.")]
 		void IUtilityCommand.Run(Utility utility, string[] args)
 		{
 			// HACK: The engine code assumes that Game.modData is set.
 			var modData = Game.ModData = utility.ModData;
+			warningAsError = Environment.GetEnvironmentVariable("TREAT_WARNINGS_AS_ERRORS")?.Equals("true", StringComparison.CurrentCultureIgnoreCase) ?? false;
 
 			try
 			{
@@ -77,7 +80,7 @@ namespace OpenRA.Mods.Common.UtilityCommands
 						try
 						{
 							var customPass = (ILintPass)modData.ObjectCreator.CreateBasic(customPassType);
-							customPass.Run(EmitError, EmitWarning, modData);
+							customPass.Run(EmitError, warningAsError ? EmitError : EmitWarning, modData);
 						}
 						catch (Exception e)
 						{
@@ -140,7 +143,7 @@ namespace OpenRA.Mods.Common.UtilityCommands
 				try
 				{
 					var customMapPass = (ILintMapPass)modData.ObjectCreator.CreateBasic(customMapPassType);
-					customMapPass.Run(EmitError, EmitWarning, modData, map);
+					customMapPass.Run(EmitError, warningAsError ? EmitError : EmitWarning, modData, map);
 				}
 				catch (Exception e)
 				{
@@ -156,7 +159,7 @@ namespace OpenRA.Mods.Common.UtilityCommands
 				try
 				{
 					var customRulesPass = (ILintRulesPass)modData.ObjectCreator.CreateBasic(customRulesPassType);
-					customRulesPass.Run(EmitError, EmitWarning, modData, rules);
+					customRulesPass.Run(EmitError, warningAsError ? EmitError : EmitWarning, modData, rules);
 				}
 				catch (Exception e)
 				{
@@ -172,7 +175,7 @@ namespace OpenRA.Mods.Common.UtilityCommands
 				try
 				{
 					var customRulesPass = (ILintSequencesPass)modData.ObjectCreator.CreateBasic(customSequencesPassType);
-					customRulesPass.Run(EmitError, EmitWarning, modData, rules, sequences);
+					customRulesPass.Run(EmitError, warningAsError ? EmitError : EmitWarning, modData, rules, sequences);
 				}
 				catch (Exception e)
 				{