diff --git a/loader/src/main/java/net/neoforged/fml/loading/moddiscovery/ModInfo.java b/loader/src/main/java/net/neoforged/fml/loading/moddiscovery/ModInfo.java
index 2872daf1a..73a5aa97e 100644
--- a/loader/src/main/java/net/neoforged/fml/loading/moddiscovery/ModInfo.java
+++ b/loader/src/main/java/net/neoforged/fml/loading/moddiscovery/ModInfo.java
@@ -203,8 +203,6 @@ private ForgeFeature.Bound makeBound(Map.Entry<String, Object> e) {
     }
 
     class ModVersion implements net.neoforged.neoforgespi.language.IModInfo.ModVersion {
-        public static final boolean MANDATORY_DEPRECATION_CRASH = !Boolean.parseBoolean(System.getProperty("fml.disableDependencyMandatoryDeprecation", "false"));
-
         private IModInfo owner;
         private final String modId;
         private final VersionRange versionRange;
@@ -224,7 +222,7 @@ public ModVersion(final IModInfo owner, final IConfigurable config) {
                         if (mandatory.isPresent()) {
                             if (!FMLLoader.isProduction()) {
                                 LOGGER.error("Mod '{}' uses deprecated 'mandatory' field in the dependency declaration for '{}'. Use the 'type' field and 'required'/'optional' instead", owner.getModId(), modId);
-                                if (MANDATORY_DEPRECATION_CRASH) {
+                                if (owner.getOwningFile().getFile().getProvider() instanceof ExplodedDirectoryLocator) {
                                     throw new InvalidModFileException("Deprecated 'mandatory' field is used in dependency", getOwningFile());
                                 }
                             }