diff --git a/src/common.rs b/src/common.rs
index 7adfa11..40d1ae7 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -101,8 +101,6 @@ pub fn get_diff_ratio(ops: &[DiffOp], old_len: usize, new_len: usize) -> f32 {
 /// This will leave holes behind in long periods of equal ranges so that
 /// you can build things like unified diffs.
 pub fn group_diff_ops(mut ops: Vec<DiffOp>, n: usize) -> Vec<Vec<DiffOp>> {
-    assert!(n > 0, "n must be 1 or larger");
-
     if ops.is_empty() {
         return vec![];
     }
diff --git a/src/text/mod.rs b/src/text/mod.rs
index bdc75a0..23408e6 100644
--- a/src/text/mod.rs
+++ b/src/text/mod.rs
@@ -760,10 +760,12 @@ fn test_serde_ops() {
 }
 
 #[test]
-#[should_panic = "n must be 1 or larger"]
 fn test_regression_issue_37() {
     let config = TextDiffConfig::default();
-    let diff = config.diff_lines("", "");
+    let diff = config.diff_lines("\u{18}\n\n", "\n\n\r");
     let mut output = diff.unified_diff();
-    output.context_radius(0).to_string();
+    assert_eq!(
+        output.context_radius(0).to_string(),
+        "@@ -1 +1,0 @@\n-\u{18}\n@@ -2,0 +2,2 @@\n+\n+\r"
+    );
 }
diff --git a/src/udiff.rs b/src/udiff.rs
index d975068..c65609e 100644
--- a/src/udiff.rs
+++ b/src/udiff.rs
@@ -57,7 +57,7 @@ impl UnifiedDiffHunkRange {
 impl fmt::Display for UnifiedDiffHunkRange {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let mut beginning = self.start() + 1;
-        let len = self.end() - self.start();
+        let len = self.end().saturating_sub(self.start());
         if len == 1 {
             write!(f, "{}", beginning)
         } else {