diff --git a/src/PersonObjects/formulas/skill.ts b/src/PersonObjects/formulas/skill.ts
index 5d9c8a895..405e90254 100644
--- a/src/PersonObjects/formulas/skill.ts
+++ b/src/PersonObjects/formulas/skill.ts
@@ -10,7 +10,21 @@ export function calculateSkill(exp: number, mult = 1): number {
 }
 
 export function calculateExp(skill: number, mult = 1): number {
-  const value = Math.exp((skill / mult + 200) / 32) - 534.6;
+  const floorSkill = Math.floor(skill);
+  let value = Math.exp((skill / mult + 200) / 32) - 534.6;
+  if (skill === floorSkill && Number.isFinite(skill)) {
+    // Check for floating point rounding issues that would cause the inverse
+    // operation to return the wrong result.
+    let calcSkill = calculateSkill(value, mult);
+    let diff = Math.abs(value * Number.EPSILON);
+    let newValue = value;
+    while (calcSkill < skill) {
+      newValue = value + diff;
+      diff *= 2;
+      calcSkill = calculateSkill(newValue, mult);
+    }
+    value = newValue;
+  }
   return clampNumber(value, 0);
 }
 
diff --git a/test/jest/formulas/Skill.test.ts b/test/jest/formulas/Skill.test.ts
new file mode 100644
index 000000000..3e2870242
--- /dev/null
+++ b/test/jest/formulas/Skill.test.ts
@@ -0,0 +1,34 @@
+import { calculateSkill, calculateExp } from "../../../src/PersonObjects/formulas/skill";
+
+describe("calculateSkill", () => {
+  test.each([...new Array(300).keys()])("Correct inverse %i", (skill: number) => {
+    if (skill < 2) return; // There are special cases to be dealt with
+    const xp1 = calculateExp(skill);
+    expect(calculateSkill(xp1)).toBe(skill);
+    expect(calculateSkill(xp1 * 0.999999999)).toBe(skill - 1);
+
+    const xp2 = calculateExp(skill, 1.4);
+    expect(calculateSkill(xp2, 1.4)).toBe(skill);
+    expect(calculateSkill(xp2 * 0.999999999, 1.4)).toBe(skill - 1);
+
+    if (skill < 4) return; // 3 is a special case for this mult
+    const xp3 = calculateExp(skill, 3.3);
+    expect(calculateSkill(xp3, 3.3)).toBe(skill);
+    expect(calculateSkill(xp3 * 0.999999999, 3.3)).toBe(skill - 1);
+    expect(calculateSkill(calculateExp(skill, 3.3), 3.3)).toBe(skill);
+  });
+  test("Special cases", () => {
+    expect(() => calculateExp(NaN)).toThrow();
+    expect(calculateExp(Infinity)).toBe(Number.MAX_VALUE);
+    expect(calculateExp(-Infinity)).toBe(0);
+
+    // In all these cases, the XP is clamped to 0. With a big enough mult,
+    // this gets converted back to a larger skill.
+    expect(calculateSkill(calculateExp(0))).toBe(1);
+    expect(calculateSkill(calculateExp(0, 1.4), 1.4)).toBe(1);
+    expect(calculateSkill(calculateExp(0, 3.3), 3.3)).toBe(3);
+    expect(calculateSkill(calculateExp(1))).toBe(1);
+    expect(calculateSkill(calculateExp(1, 1.4), 1.4)).toBe(1);
+    expect(calculateSkill(calculateExp(1, 3.3), 3.3)).toBe(3);
+  });
+});