diff --git a/src/main/java/sk/tomsik68/mclauncher/api/mods/IModdingProfile.java b/src/main/java/sk/tomsik68/mclauncher/api/mods/IModdingProfile.java
index 176c029..ca47862 100644
--- a/src/main/java/sk/tomsik68/mclauncher/api/mods/IModdingProfile.java
+++ b/src/main/java/sk/tomsik68/mclauncher/api/mods/IModdingProfile.java
@@ -1,6 +1,5 @@
 package sk.tomsik68.mclauncher.api.mods;
 
-import sk.tomsik68.mclauncher.impl.versions.mcdownload.Library;
 
 import java.io.File;
 import java.util.List;
@@ -25,10 +24,10 @@ public interface IModdingProfile {
 
     /**
      *
-     * @param library
+     * @param libraryName - Name of library to test
      * @return True if specified library may be injected along with all vanilla libraries
      */
-    public boolean isLibraryAllowed(Library library);
+    public boolean isLibraryAllowed(String libraryName);
 
     /**
      *
diff --git a/src/main/java/sk/tomsik68/mclauncher/impl/common/Platform.java b/src/main/java/sk/tomsik68/mclauncher/impl/common/Platform.java
index bf15589..99b4c39 100644
--- a/src/main/java/sk/tomsik68/mclauncher/impl/common/Platform.java
+++ b/src/main/java/sk/tomsik68/mclauncher/impl/common/Platform.java
@@ -1,7 +1,6 @@
 package sk.tomsik68.mclauncher.impl.common;
 
 import sk.tomsik68.mclauncher.api.common.IOperatingSystem;
-import sk.tomsik68.mclauncher.impl.versions.mcdownload.Library;
 
 import java.util.HashMap;
 import java.util.LinkedList;
@@ -38,7 +37,6 @@ public static IOperatingSystem getCurrentPlatform() {
 
     public static void forcePlatform(IOperatingSystem p) {
         currentOS = p;
-        Library.addLibraryPathVariable("arch", currentOS.getArchitecture());
     }
 
     public static String wrapName(String name) {
diff --git a/src/main/java/sk/tomsik68/mclauncher/impl/versions/mcdownload/Library.java b/src/main/java/sk/tomsik68/mclauncher/impl/versions/mcdownload/Library.java
index e162b93..d3771b2 100644
--- a/src/main/java/sk/tomsik68/mclauncher/impl/versions/mcdownload/Library.java
+++ b/src/main/java/sk/tomsik68/mclauncher/impl/versions/mcdownload/Library.java
@@ -12,8 +12,8 @@
 import java.util.ArrayList;
 import java.util.HashMap;
 
-public class Library {
-    private static final StringSubstitutor libraryPathSubstitutor = new StringSubstitutor("${%s}");
+final class Library {
+    private final StringSubstitutor libraryPathSubstitutor = new StringSubstitutor("${%s}");
     private final String name;
     private final HashMap<String, String> natives = new HashMap<String, String>();
     private final ArrayList<Rule> rules = new ArrayList<Rule>();
@@ -46,10 +46,6 @@ public Library(JSONObject json) {
         }
     }
 
-    public static void addLibraryPathVariable(String key, String value) {
-        libraryPathSubstitutor.setVariable(key, value);
-    }
-
     public String getName() {
         return name;
     }
@@ -61,6 +57,7 @@ public String getNatives(IOperatingSystem os) {
     }
 
     public String getPath() {
+        libraryPathSubstitutor.setVariable("arch", Platform.getCurrentPlatform().getArchitecture());
         String[] split = name.split(":");
         StringBuilder result = new StringBuilder();