diff --git a/src/main/java/net/fabricmc/loom/configuration/providers/forge/ForgeRunTemplate.java b/src/main/java/net/fabricmc/loom/configuration/providers/forge/ForgeRunTemplate.java
index b1d4f985f8..cf068cbfa5 100644
--- a/src/main/java/net/fabricmc/loom/configuration/providers/forge/ForgeRunTemplate.java
+++ b/src/main/java/net/fabricmc/loom/configuration/providers/forge/ForgeRunTemplate.java
@@ -58,13 +58,13 @@ public void applyTo(RunConfigSettings settings, ConfigValue.Resolver configValue
 
 		settings.vmArgs(CollectionUtil.map(jvmArgs, value -> value.resolve(configValueResolver)));
 
-		// Add MOD_CLASSES, this is something that ForgeGradle does
-		env.computeIfAbsent("MOD_CLASSES", $ -> ConfigValue.of("{source_roots}"));
-
 		env.forEach((key, value) -> {
 			String resolved = value.resolve(configValueResolver);
 			settings.getEnvironmentVariables().putIfAbsent(key, resolved);
 		});
+
+		// Add MOD_CLASSES, this is something that ForgeGradle does
+		settings.getEnvironmentVariables().computeIfAbsent("MOD_CLASSES", $ -> ConfigValue.of("{source_roots}").resolve(configValueResolver));
 	}
 
 	public static ForgeRunTemplate fromJson(JsonObject json) {