diff --git a/LaunchServer/source/auth/handler/TextFileAuthHandler.java b/LaunchServer/source/auth/handler/TextFileAuthHandler.java
index b941e59..97f6849 100644
--- a/LaunchServer/source/auth/handler/TextFileAuthHandler.java
+++ b/LaunchServer/source/auth/handler/TextFileAuthHandler.java
@@ -9,6 +9,7 @@
 import java.util.UUID;
 
 import launcher.helper.IOHelper;
+import launcher.helper.VerifyHelper;
 import launcher.serialize.config.TextConfigReader;
 import launcher.serialize.config.TextConfigWriter;
 import launcher.serialize.config.entry.BlockConfigEntry;
@@ -31,10 +32,8 @@
 		Set<Map.Entry<String, ConfigEntry<?>>> entrySet = authFile.getValue().entrySet();
 		for (Map.Entry<String, ConfigEntry<?>> entry : entrySet) {
 			UUID uuid = UUID.fromString(entry.getKey());
-			ConfigEntry<?> value = entry.getValue();
-			if (value.getType() != ConfigEntry.Type.BLOCK) {
-				throw new IOException("Unsupported config entry type: " + uuid);
-			}
+			ConfigEntry<?> value = VerifyHelper.verify(entry.getValue(),
+				v -> v.getType() == ConfigEntry.Type.BLOCK, "Illegal config entry type: " + uuid);
 
 			// Get auth entry data
 			BlockConfigEntry authBlock = (BlockConfigEntry) value;
diff --git a/LaunchServer/source/auth/provider/FileAuthProvider.java b/LaunchServer/source/auth/provider/FileAuthProvider.java
index f8eda3a..a9e3feb 100644
--- a/LaunchServer/source/auth/provider/FileAuthProvider.java
+++ b/LaunchServer/source/auth/provider/FileAuthProvider.java
@@ -9,6 +9,7 @@
 
 import launcher.helper.IOHelper;
 import launcher.helper.LogHelper;
+import launcher.helper.VerifyHelper;
 import launcher.serialize.config.entry.BlockConfigEntry;
 import launcher.serialize.config.entry.StringConfigEntry;
 import launchserver.helper.LineReader;
@@ -54,22 +55,18 @@
 		try (BufferedReader reader = new LineReader(IOHelper.newReader(file))) {
 			for (String line = reader.readLine(); line != null; line = reader.readLine()) {
 				// Get and verify split index
-				int splitIndex = line.indexOf(':');
-				if (splitIndex < 0) {
-					throw new IOException(String.format("Illegal line in users file: '%s'", line));
-				}
+				int splitIndex = VerifyHelper.verifyInt(line.indexOf(':'), VerifyHelper.NOT_NEGATIVE,
+					String.format("Illegal line in users file: '%s'", line));
 
 				// Split and verify username and password
-				String username = line.substring(0, splitIndex).trim();
-				String password = line.substring(splitIndex + 1).trim();
-				if (username.isEmpty() || password.isEmpty()) {
-					throw new IOException(String.format("Empty username or password in users file: '%s'", line));
-				}
+				String username = VerifyHelper.verify(line.substring(0, splitIndex).trim(),
+					VerifyHelper.NOT_EMPTY, "Empty username");
+				String password = VerifyHelper.verify(line.substring(splitIndex + 1).trim(),
+					VerifyHelper.NOT_EMPTY, "Empty pasword");
 
 				// Try put to cache
-				if (cache.put(username, password) != null) {
-					throw new IOException(String.format("Duplicate username in users file: '%s'", username));
-				}
+				VerifyHelper.putIfAbsent(cache, username, password,
+					String.format("Duplicate username in users file: '%s'", username));
 			}
 		}
 
diff --git a/LaunchServer/source/response/ServerSocketHandler.java b/LaunchServer/source/response/ServerSocketHandler.java
index 8504e29..e1db91b 100644
--- a/LaunchServer/source/response/ServerSocketHandler.java
+++ b/LaunchServer/source/response/ServerSocketHandler.java
@@ -57,7 +57,7 @@
 		LogHelper.info("Starting server socket thread");
 		try (ServerSocket serverSocket = new ServerSocket()) {
 			if (!this.serverSocket.compareAndSet(null, serverSocket)) {
-				throw new IOException("Previous socket wasn'sizet closed");
+				throw new IllegalStateException("Previous socket wasn't closed");
 			}
 
 			// Set socket params
@@ -88,10 +88,8 @@
 
 	@LauncherAPI
 	public Response newCustomResponse(String name, HInput input, HOutput output) throws IOException {
-		Response.Factory factory = customResponses.get(name);
-		if (factory == null) {
-			throw new IOException(String.format("Unknown custom response: '%s'", name));
-		}
+		Response.Factory factory = VerifyHelper.getMapValue(customResponses, name,
+			String.format("Unknown custom response: '%s'", name));
 		return factory.newResponse(server, input, output);
 	}
 
diff --git a/Launcher/source/hasher/DirWatcher.java b/Launcher/source/hasher/DirWatcher.java
index 07adbe0..32ae5a7 100644
--- a/Launcher/source/hasher/DirWatcher.java
+++ b/Launcher/source/hasher/DirWatcher.java
@@ -99,7 +99,8 @@
 			}
 
 			// Forbidden modification!
-			throw new SecurityException(String.format("Forbidden modification (%s, %d times): '%s'", kind, event.count(), path));
+			throw new SecurityException(String.format("Forbidden modification (%s, %d times): '%s'",
+				kind, event.count(), path));
 		}
 		key.reset();
 	}
diff --git a/Launcher/source/hasher/HashedDir.java b/Launcher/source/hasher/HashedDir.java
index de81114..f54bdb4 100644
--- a/Launcher/source/hasher/HashedDir.java
+++ b/Launcher/source/hasher/HashedDir.java
@@ -14,6 +14,7 @@
 
 import launcher.LauncherAPI;
 import launcher.helper.IOHelper;
+import launcher.helper.VerifyHelper;
 import launcher.serialize.HInput;
 import launcher.serialize.HOutput;
 import launcher.serialize.stream.EnumSerializer;
@@ -35,9 +36,6 @@
 		int entriesCount = input.readLength(0);
 		for (int i = 0; i < entriesCount; i++) {
 			String name = IOHelper.verifyFileName(input.readString(255));
-			if (map.containsKey(name)) {
-				throw new IOException(String.format("Duplicate hashed entry: '%s'", name));
-			}
 
 			// Read entry
 			HashedEntry entry;
@@ -54,9 +52,7 @@
 			}
 
 			// Try add entry to map
-			if (map.put(name, entry) != null) {
-				throw new IOException(String.format("Duplicate dir entry: '%s'", name));
-			}
+			VerifyHelper.putIfAbsent(map, name, entry, String.format("Duplicate dir entry: '%s'", name));
 		}
 	}
 
diff --git a/Launcher/source/helper/IOHelper.java b/Launcher/source/helper/IOHelper.java
index 8dbb3d5..6c16ea7 100644
--- a/Launcher/source/helper/IOHelper.java
+++ b/Launcher/source/helper/IOHelper.java
@@ -470,7 +470,7 @@
 		try {
 			return path.toUri().toURL();
 		} catch (MalformedURLException e) {
-			throw new AssertionError(e);
+			throw new InternalError(e);
 		}
 	}
 
diff --git a/Launcher/source/helper/JVMHelper.java b/Launcher/source/helper/JVMHelper.java
index 617834a..ea94e50 100644
--- a/Launcher/source/helper/JVMHelper.java
+++ b/Launcher/source/helper/JVMHelper.java
@@ -170,7 +170,7 @@
 			if (name.startsWith("Mac OS X")) {
 				return MACOSX;
 			}
-			throw new IllegalArgumentException(String.format("This shit is not yet supported: '%s'", name));
+			throw new RuntimeException(String.format("This shit is not yet supported: '%s'", name));
 		}
 	}
 }
diff --git a/Launcher/source/request/update/UpdateRequest.java b/Launcher/source/request/update/UpdateRequest.java
index e685a0b..e99a64a 100644
--- a/Launcher/source/request/update/UpdateRequest.java
+++ b/Launcher/source/request/update/UpdateRequest.java
@@ -196,7 +196,7 @@
 		// Verify digest
 		byte[] digestBytes = digest.digest();
 		if (!hFile.isSameDigest(digestBytes)) {
-			throw new IOException(String.format("File digest mismatch: '%s'", filePath));
+			throw new SecurityException(String.format("File digest mismatch: '%s'", filePath));
 		}
 	}
 
diff --git a/Launcher/source/serialize/config/entry/BlockConfigEntry.java b/Launcher/source/serialize/config/entry/BlockConfigEntry.java
index dfe8192..5fae5e4 100644
--- a/Launcher/source/serialize/config/entry/BlockConfigEntry.java
+++ b/Launcher/source/serialize/config/entry/BlockConfigEntry.java
@@ -101,9 +101,7 @@
 			ConfigEntry<?> entry = readEntry(input, ro);
 
 			// Try add entry to map
-			if (map.put(name, entry) != null) {
-				throw new IOException(String.format("Duplicate config entry: '%s'", name));
-			}
+			VerifyHelper.putIfAbsent(map, name, entry, String.format("Duplicate config entry: '%s'", name));
 		}
 		return map;
 	}
diff --git a/Launcher/source/serialize/config/entry/ConfigEntry.java b/Launcher/source/serialize/config/entry/ConfigEntry.java
index f550ec1..0c4e7ea 100644
--- a/Launcher/source/serialize/config/entry/ConfigEntry.java
+++ b/Launcher/source/serialize/config/entry/ConfigEntry.java
@@ -73,7 +73,7 @@
 			case BLOCK:
 				return new BlockConfigEntry(input, ro);
 			default:
-				throw new IOException("Unsupported config entry type: " + type.name());
+				throw new AssertionError("Unsupported config entry type: " + type.name());
 		}
 	}
 
diff --git a/Launcher/source/serialize/stream/EnumSerializer.java b/Launcher/source/serialize/stream/EnumSerializer.java
index 91f083c..a8fef48 100644
--- a/Launcher/source/serialize/stream/EnumSerializer.java
+++ b/Launcher/source/serialize/stream/EnumSerializer.java
@@ -6,6 +6,7 @@
 import java.util.Map;
 
 import launcher.LauncherAPI;
+import launcher.helper.VerifyHelper;
 import launcher.serialize.HInput;
 import launcher.serialize.HOutput;
 import launcher.serialize.stream.EnumSerializer.Itf;
@@ -25,7 +26,7 @@
 			try {
 				itf = (Itf) field.get(null);
 			} catch (IllegalAccessException e) {
-				throw new RuntimeException(e);
+				throw new InternalError(e);
 			}
 			map.put(itf.getNumber(), clazz.cast(itf));
 		}
@@ -34,11 +35,7 @@
 	@LauncherAPI
 	public E read(HInput input) throws IOException {
 		int n = input.readVarInt();
-		E e = map.get(n);
-		if (e == null) {
-			throw new IOException("Unknown enum number: " + n);
-		}
-		return e;
+		return VerifyHelper.getMapValue(map, n, "Unknown enum number: " + n);
 	}
 
 	@LauncherAPI