diff --git a/tamer/src/diagnose/report.rs b/tamer/src/diagnose/report.rs
index fdccf6fe..e249820c 100644
--- a/tamer/src/diagnose/report.rs
+++ b/tamer/src/diagnose/report.rs
@@ -20,8 +20,8 @@
 //! Rendering of diagnostic information.
 
 use super::{
-    AnnotatedSpan, Diagnostic, Label, Level, ResolvedSpan,
-    SpanResolver, SpanResolverError,
+    AnnotatedSpan, Diagnostic, Label, Level, ResolvedSpan, SpanResolver,
+    SpanResolverError,
 };
 use crate::span::{Context, Span, UNKNOWN_SPAN};
 use std::fmt::{self, Display, Write};
diff --git a/tamer/src/diagnose/resolver.rs b/tamer/src/diagnose/resolver.rs
index 1e687eab..2e30fd39 100644
--- a/tamer/src/diagnose/resolver.rs
+++ b/tamer/src/diagnose/resolver.rs
@@ -177,9 +177,6 @@ impl ResolvedSpan {
 ///     with font rather than a byte offset.
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
 pub enum Column {
-    /// A 1-indexed column number.
-    At(NonZeroU32),
-
     /// A range of 1-indexed columns, inclusive.
     Endpoints(NonZeroU32, NonZeroU32),
 
@@ -196,9 +193,7 @@ impl Display for Column {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
             // Coerces to a single column number.
-            Self::At(at) | Self::Endpoints(at, _) | Self::Before(at) => {
-                Display::fmt(at, f)
-            }
+            Self::Endpoints(at, _) | Self::Before(at) => Display::fmt(at, f),
         }
     }
 }
@@ -631,10 +626,8 @@ impl Line {
         // Start will only be > end (by 1) if the span begins on a newline.
         if span.len() == 0 {
             Column::Before(col_start)
-        } else if col_start >= col_end {
-            Column::At(col_start)
         } else {
-            Column::Endpoints(col_start, col_end)
+            Column::Endpoints(col_start, col_end.max(col_start))
         }
     }
 
diff --git a/tamer/src/diagnose/resolver/test.rs b/tamer/src/diagnose/resolver/test.rs
index 0d7d7b11..9b950bea 100644
--- a/tamer/src/diagnose/resolver/test.rs
+++ b/tamer/src/diagnose/resolver/test.rs
@@ -119,7 +119,10 @@ fn last_byte_of_line() {
             span,
             lines: NonEmptyVec::new(vec![SourceLine {
                 num: 3.unwrap_into(),
-                column: Some(Column::At(6.unwrap_into(),)),
+                column: Some(Column::Endpoints(
+                    6.unwrap_into(),
+                    6.unwrap_into()
+                )),
                 span: ctx.span(14, 6),
                 text: "line 3".into(),
             }])
@@ -322,7 +325,10 @@ fn newline_between_lines() {
             span,
             lines: NonEmptyVec::new(vec![SourceLine {
                 num: 2.unwrap_into(),
-                column: Some(Column::At(7.unwrap_into())),
+                column: Some(Column::Endpoints(
+                    7.unwrap_into(),
+                    7.unwrap_into()
+                )),
                 // Trailing newline _is not_ stripped since it was
                 //   explicitly referenced;
                 //     we don't want our line span to not contain the
@@ -744,7 +750,10 @@ fn at_invalid_char_boundary() {
                 // Intuitively this really should be [2,4],
                 //   but the implementation shouldn't change to
                 //   accommodate this very unlikely case.
-                column: Some(Column::At(4.unwrap_into(),)),
+                column: Some(Column::Endpoints(
+                    4.unwrap_into(),
+                    4.unwrap_into()
+                )),
                 span: line_span,
                 text: buf.clone().into(),
             }])
@@ -760,7 +769,10 @@ fn at_invalid_char_boundary() {
                 num: 1.unwrap_into(),
                 // Also unideal,
                 //   but see comment for previous assertion.
-                column: Some(Column::At(4.unwrap_into(),)),
+                column: Some(Column::Endpoints(
+                    4.unwrap_into(),
+                    4.unwrap_into()
+                )),
                 span: line_span,
                 text: buf.clone().into(),
             }])