diff --git a/src/test/java/com/mattrixwv/cipherstream/polysubstitution/TestRailFence.java b/src/test/java/com/mattrixwv/cipherstream/polysubstitution/TestRailFence.java
index 72dd0a6..c79d64b 100644
--- a/src/test/java/com/mattrixwv/cipherstream/polysubstitution/TestRailFence.java
+++ b/src/test/java/com/mattrixwv/cipherstream/polysubstitution/TestRailFence.java
@@ -301,6 +301,27 @@ public class TestRailFence{
 		verify(logger, times(1)).debug("Fence output '{}'", decodedString.replaceAll("[^a-zA-Z]", ""));
 	}
 
+	@Test
+	public void testDecode_length(){
+		cipher.inputString = "aa";
+		cipher.fence = new StringBuilder[]{
+			new StringBuilder(),
+			new StringBuilder(),
+			new StringBuilder()
+		};
+
+		cipher.decode();
+
+		assertEquals("aa", cipher.outputString);
+		verify(logger, times(1)).debug("Decoding");
+		verify(logger, times(1)).debug("Number of characters in the top rail {}", 1);
+		verify(logger, times(1)).debug("Number of characters in the middle rails {}", 1);
+		verify(logger, times(1)).debug("Number of characters in the bottom rail {}", 0);
+		verify(logger, times(1)).debug("Adding characters to the rails");
+		verify(logger, times(1)).debug("Appending the bottom rail");
+		verify(logger, times(1)).debug("Fence output '{}'", "aa");
+	}
+
 	@Test
 	public void testGetters(){
 		cipher.inputString = decodedString;
diff --git a/src/test/java/com/mattrixwv/cipherstream/polysubstitution/TestTrifid.java b/src/test/java/com/mattrixwv/cipherstream/polysubstitution/TestTrifid.java
index c00704a..3bb65ef 100644
--- a/src/test/java/com/mattrixwv/cipherstream/polysubstitution/TestTrifid.java
+++ b/src/test/java/com/mattrixwv/cipherstream/polysubstitution/TestTrifid.java
@@ -204,7 +204,7 @@ public class TestTrifid{
 	}
 
 	@Test
-	public void testSetFillIn_nonPrinting(){
+	public void testSetFillIn_nonPrintingLow(){
 		assertThrows(InvalidCharacterException.class, () -> {
 			cipher.setFillIn('\0');
 		});
@@ -213,6 +213,16 @@ public class TestTrifid{
 		verify(logger, never()).debug(eq("Setting fill in {}"), anyChar());
 	}
 
+	@Test
+	public void testSetFill_nonPrintingHigh(){
+		assertThrows(InvalidCharacterException.class, () -> {
+			cipher.setFillIn((char)127);
+		});
+
+		assertEquals('+', cipher.fillIn);
+		verify(logger, never()).debug(eq("Setting fill in {}"), anyChar());
+	}
+
 	@Test
 	public void testSetFillIn_letter(){
 		assertThrows(InvalidCharacterException.class, () -> {