diff --git a/loader/src/main/java/net/neoforged/fml/loading/moddiscovery/locators/JarInJarDependencyLocator.java b/loader/src/main/java/net/neoforged/fml/loading/moddiscovery/locators/JarInJarDependencyLocator.java
index 8ad140cbf..c8ed394e8 100644
--- a/loader/src/main/java/net/neoforged/fml/loading/moddiscovery/locators/JarInJarDependencyLocator.java
+++ b/loader/src/main/java/net/neoforged/fml/loading/moddiscovery/locators/JarInJarDependencyLocator.java
@@ -109,9 +109,14 @@ private String formatError(final ModWithVersionRange modWithVersionRange) {
     }
 
     protected String identifyMod(final IModFile modFile) {
-        if (modFile.getModFileInfo() == null || modFile.getModInfos().isEmpty()) {
+        if (modFile.getModFileInfo() == null) {
             return modFile.getFileName();
         }
+        // If this is a library, it won't have any mod IDs, so we use the module name instead.
+        if (modFile.getModInfos().isEmpty()) {
+            // Prefix to ensure this cannot collide with any true mod ID.
+            return "library:" + modFile.getModFileInfo().moduleName();
+        }
 
         return modFile.getModInfos().stream().map(IModInfo::getModId).collect(Collectors.joining());
     }
diff --git a/loader/src/main/java/net/neoforged/fml/loading/moddiscovery/readers/JarModsDotTomlModFileReader.java b/loader/src/main/java/net/neoforged/fml/loading/moddiscovery/readers/JarModsDotTomlModFileReader.java
index cc26d5af2..519b082e9 100644
--- a/loader/src/main/java/net/neoforged/fml/loading/moddiscovery/readers/JarModsDotTomlModFileReader.java
+++ b/loader/src/main/java/net/neoforged/fml/loading/moddiscovery/readers/JarModsDotTomlModFileReader.java
@@ -140,12 +140,12 @@ public IConfigurable getConfig() {
             return configurable;
         }
 
-        // These Should never be called as it's only called from ModJarMetadata.version and we bypass that
         @Override
         public String moduleName() {
             return mod.getSecureJar().name();
         }
 
+        // These Should never be called as it's only called from ModJarMetadata.version and we bypass that
         @Override
         public String versionString() {
             return null;