diff --git a/core/src/com/riiablo/io/BitConstraints.java b/core/src/com/riiablo/io/BitConstraints.java
index 1bec93c2..c1a047ca 100644
--- a/core/src/com/riiablo/io/BitConstraints.java
+++ b/core/src/com/riiablo/io/BitConstraints.java
@@ -1,6 +1,6 @@
 package com.riiablo.io;
 
-class BitConstraints {
+public class BitConstraints {
   private BitConstraints() {}
 
   private static int _validateSize(int min, int max, int bits) {
@@ -60,33 +60,65 @@ class BitConstraints {
     return _validateSize(Byte.SIZE - 1, Byte.SIZE, bits);
   }
 
-  public static byte safe8u(short i) {
+  public static byte safe8u(ByteInput byteInput, short i) {
     if (!BitUtils.isUnsigned(i, Byte.SIZE)) {
-      throw new UnsafeNarrowing(i);
+      throw new UnsafeNarrowing(byteInput, i);
     }
 
     return (byte) i;
   }
 
-  public static short safe16u(int i) {
+  public static short safe16u(ByteInput byteInput, int i) {
     if (!BitUtils.isUnsigned(i, Short.SIZE)) {
-      throw new UnsafeNarrowing(i);
+      throw new UnsafeNarrowing(byteInput, i);
     }
 
     return (short) i;
   }
 
-  public static int safe32u(long i) {
+  public static int safe32u(ByteInput byteInput, long i) {
     if (!BitUtils.isUnsigned(i, Integer.SIZE)) {
-      throw new UnsafeNarrowing(i);
+      throw new UnsafeNarrowing(byteInput, i);
     }
 
     return (int) i;
   }
 
-  public static long safe64u(long i) {
+  public static long safe64u(ByteInput byteInput, long i) {
     if (!BitUtils.isUnsigned(i, Long.SIZE)) {
-      throw new UnsafeNarrowing(i);
+      throw new UnsafeNarrowing(byteInput, i);
+    }
+
+    return (long) i;
+  }
+
+  public static byte safe8u(BitInput bitInput, short i) {
+    if (!BitUtils.isUnsigned(i, Byte.SIZE)) {
+      throw new UnsafeNarrowing(bitInput.byteInput(), i);
+    }
+
+    return (byte) i;
+  }
+
+  public static short safe16u(BitInput bitInput, int i) {
+    if (!BitUtils.isUnsigned(i, Short.SIZE)) {
+      throw new UnsafeNarrowing(bitInput.byteInput(), i);
+    }
+
+    return (short) i;
+  }
+
+  public static int safe32u(BitInput bitInput, long i) {
+    if (!BitUtils.isUnsigned(i, Integer.SIZE)) {
+      throw new UnsafeNarrowing(bitInput.byteInput(), i);
+    }
+
+    return (int) i;
+  }
+
+  public static long safe64u(BitInput bitInput, long i) {
+    if (!BitUtils.isUnsigned(i, Long.SIZE)) {
+      throw new UnsafeNarrowing(bitInput.byteInput(), i);
     }
 
     return (long) i;
diff --git a/core/src/com/riiablo/io/BitInput.java b/core/src/com/riiablo/io/BitInput.java
index b37c0a34..c9b24582 100644
--- a/core/src/com/riiablo/io/BitInput.java
+++ b/core/src/com/riiablo/io/BitInput.java
@@ -459,7 +459,7 @@ public class BitInput {
   public byte readSafe8u() {
     try {
       final short value = read8u();
-      return BitConstraints.safe8u(value);
+      return BitConstraints.safe8u(byteInput, value);
     } catch (IndexOutOfBoundsException t) {
       throw new EndOfInput(t);
     }
@@ -475,7 +475,7 @@ public class BitInput {
   public short readSafe16u() {
     try {
       final int value = read16u();
-      return BitConstraints.safe16u(value);
+      return BitConstraints.safe16u(byteInput, value);
     } catch (IndexOutOfBoundsException t) {
       throw new EndOfInput(t);
     }
@@ -491,7 +491,7 @@ public class BitInput {
   public int readSafe32u() {
     try {
       final long value = read32u();
-      return BitConstraints.safe32u(value);
+      return BitConstraints.safe32u(byteInput, value);
     } catch (IndexOutOfBoundsException t) {
       throw new EndOfInput(t);
     }
@@ -507,7 +507,7 @@ public class BitInput {
   public long readSafe64u() {
     try {
       final long value = read64();
-      return BitConstraints.safe64u(value);
+      return BitConstraints.safe64u(byteInput, value);
     } catch (IndexOutOfBoundsException t) {
       throw new EndOfInput(t);
     }
diff --git a/core/src/com/riiablo/io/ByteInput.java b/core/src/com/riiablo/io/ByteInput.java
index e904d411..0f9c34e3 100644
--- a/core/src/com/riiablo/io/ByteInput.java
+++ b/core/src/com/riiablo/io/ByteInput.java
@@ -401,7 +401,7 @@ public class ByteInput {
     assert aligned() : "not aligned";
     try {
       final short value = read8u(); // increments bits
-      return BitConstraints.safe8u(value);
+      return BitConstraints.safe8u(this, value);
     } catch (IndexOutOfBoundsException t) {
       throw new EndOfInput(t);
     }
@@ -418,7 +418,7 @@ public class ByteInput {
     assert aligned() : "not aligned";
     try {
       final int value = read16u(); // increments bits
-      return BitConstraints.safe16u(value);
+      return BitConstraints.safe16u(this, value);
     } catch (IndexOutOfBoundsException t) {
       throw new EndOfInput(t);
     }
@@ -435,7 +435,7 @@ public class ByteInput {
     assert aligned() : "not aligned";
     try {
       final long value = read32u(); // increments bits
-      return BitConstraints.safe32u(value);
+      return BitConstraints.safe32u(this, value);
     } catch (IndexOutOfBoundsException t) {
       throw new EndOfInput(t);
     }
@@ -452,7 +452,7 @@ public class ByteInput {
     assert aligned() : "not aligned";
     try {
       final long value = read64(); // increments bits
-      return BitConstraints.safe64u(value);
+      return BitConstraints.safe64u(this, value);
     } catch (IndexOutOfBoundsException t) {
       throw new EndOfInput(t);
     }
diff --git a/core/src/com/riiablo/io/UnsafeNarrowing.java b/core/src/com/riiablo/io/UnsafeNarrowing.java
index 0d5dec86..25d99bd4 100644
--- a/core/src/com/riiablo/io/UnsafeNarrowing.java
+++ b/core/src/com/riiablo/io/UnsafeNarrowing.java
@@ -1,13 +1,19 @@
 package com.riiablo.io;
 
 public class UnsafeNarrowing extends RuntimeException {
+  public final ByteInput byteInput;
   public final long value;
 
-  UnsafeNarrowing(long value) {
+  UnsafeNarrowing(ByteInput byteInput, long value) {
     super("value(" + value + ") cannot be safely narrowed!");
+    this.byteInput = byteInput;
     this.value = value;
   }
 
+  public ByteInput byteInput() {
+    return byteInput;
+  }
+
   public short u8() {
     return (short) value;
   }