diff --git a/src/main/java/ftbsc/lll/exceptions/InvalidResourceException.java b/src/main/java/ftbsc/lll/exceptions/InvalidResourceException.java
new file mode 100644
index 0000000..dd75a08
--- /dev/null
+++ b/src/main/java/ftbsc/lll/exceptions/InvalidResourceException.java
@@ -0,0 +1,22 @@
+package ftbsc.lll.exceptions;
+
+/**
+ * Thrown when a resource passed as an argument is not found.
+ */
+public class InvalidResourceException extends RuntimeException {
+
+	/**
+	 * Empty constructor, used when the provided resource exists but is empty.
+	 */
+	public InvalidResourceException() {
+		super("The specified resource was empty!");
+	}
+
+	/**
+	 * Named constructor, used when the specified resource doesn't exist.
+	 * @param name the resource name
+	 */
+	public InvalidResourceException(String name) {
+		super("Specified resource " + name + " was not found!");
+	}
+}
diff --git a/src/main/java/ftbsc/lll/exceptions/MappingNotFoundException.java b/src/main/java/ftbsc/lll/exceptions/MappingNotFoundException.java
index a1a47d1..3334242 100644
--- a/src/main/java/ftbsc/lll/exceptions/MappingNotFoundException.java
+++ b/src/main/java/ftbsc/lll/exceptions/MappingNotFoundException.java
@@ -1,17 +1,27 @@
 package ftbsc.lll.exceptions;
 
-import ftbsc.lll.processor.tools.obfuscation.ObfuscationMapper;
+import ftbsc.lll.processor.tools.obfuscation.IMapper;
 
 /**
- * Thrown upon failure to find the requested mapping within a loaded {@link ObfuscationMapper}.
+ * Thrown upon failure to find the requested mapping within a loaded {@link IMapper}.
  */
 public class MappingNotFoundException extends RuntimeException {
 
 	/**
 	 * Constructs a new mapping not found exception for the specified mapping.
-	 * @param mapping the detail message
+	 * @param mapping the relevant mapping
 	 */
 	public MappingNotFoundException(String mapping) {
 		super("Could not find mapping for " + mapping + "!");
 	}
+
+	/**
+	 * Constructs a new mapping not found exception for the specified mapping
+	 * with the specified reason.
+	 * @param mapping the relevant mapping
+	 * @param reason the reason message
+	 */
+	public MappingNotFoundException(String mapping, String reason) {
+		this(mapping + ": " + reason);
+	}
 }
diff --git a/src/main/java/ftbsc/lll/processor/LilleroProcessor.java b/src/main/java/ftbsc/lll/processor/LilleroProcessor.java
index c6343a6..aaaa2f0 100644
--- a/src/main/java/ftbsc/lll/processor/LilleroProcessor.java
+++ b/src/main/java/ftbsc/lll/processor/LilleroProcessor.java
@@ -3,6 +3,7 @@ package ftbsc.lll.processor;
 import com.squareup.javapoet.*;
 import ftbsc.lll.IInjector;
 import ftbsc.lll.exceptions.AmbiguousDefinitionException;
+import ftbsc.lll.exceptions.InvalidResourceException;
 import ftbsc.lll.exceptions.MappingNotFoundException;
 import ftbsc.lll.exceptions.TargetNotFoundException;
 import ftbsc.lll.processor.annotations.*;
@@ -20,6 +21,8 @@ import javax.tools.FileObject;
 import javax.tools.JavaFileObject;
 import javax.tools.StandardLocation;
 import java.io.*;
+import java.net.URI;
+import java.net.URISyntaxException;
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
 import java.util.*;
@@ -61,14 +64,26 @@ public class LilleroProcessor extends AbstractProcessor {
 		String location = processingEnv.getOptions().get("mappingsFile");
 		if(location == null)
 			mapper = null;
-		else { //TODO: add local file
+		else {
+			InputStream targetStream;
 			try {
-				URL url = new URL(location);
-				InputStream is = url.openStream();
-				mapper = new ObfuscationMapper(new BufferedReader(new InputStreamReader(is,
-					StandardCharsets.UTF_8)).lines());
-				is.close();
-			} catch(IOException ignored) {} //TODO: proper handling
+				URI target = new URI(location);
+				targetStream = target.toURL().openStream();
+			} catch(URISyntaxException | IOException e) {
+				//may be a local file path
+				File f = new File(location);
+				if(!f.exists())
+					throw new InvalidResourceException(location);
+				try {
+					targetStream = new FileInputStream(f);
+				} catch(FileNotFoundException ex) {
+					throw new InvalidResourceException(location);
+				}
+			}
+			//assuming its tsrg file
+			//todo: replace crappy homebaked parser with actual library
+			this.mapper = new ObfuscationMapper(new BufferedReader(new InputStreamReader(targetStream,
+				StandardCharsets.UTF_8)).lines());
 		}
 	}