diff --git a/packages/tui/src/util/locale.ts b/packages/tui/src/util/locale.ts
index 569484e37308..f9569b2751a3 100644
--- a/packages/tui/src/util/locale.ts
+++ b/packages/tui/src/util/locale.ts
@@ -17,7 +17,8 @@ export function datetime(input: number): string {
 }
 
 export function number(num: number): string {
-  if (num >= 1000000) {
+  // 999,950 and up round to 1000.0K at one decimal place, so roll over to M there
+  if (num >= 999950) {
     return (num / 1000000).toFixed(1) + "M"
   } else if (num >= 1000) {
     return (num / 1000).toFixed(1) + "K"
diff --git a/packages/tui/test/util/locale.test.ts b/packages/tui/test/util/locale.test.ts
index e3d3396884b4..ca4c2c51b631 100644
--- a/packages/tui/test/util/locale.test.ts
+++ b/packages/tui/test/util/locale.test.ts
@@ -12,3 +12,12 @@ test("takes whole graphemes within terminal width", () => {
   expect(Locale.takeWidth("ab界cd", 4)).toBe("ab界")
   expect(Locale.graphemes("a👨‍👩‍👧‍👦b")).toEqual(["a", "👨‍👩‍👧‍👦", "b"])
 })
+
+test("formats compact numbers and rolls over to M at the rounding boundary", () => {
+  expect(Locale.number(999)).toBe("999")
+  expect(Locale.number(1500)).toBe("1.5K")
+  expect(Locale.number(999949)).toBe("999.9K")
+  expect(Locale.number(999950)).toBe("1.0M")
+  expect(Locale.number(999999)).toBe("1.0M")
+  expect(Locale.number(2500000)).toBe("2.5M")
+})