diff --git a/package-lock.json b/package-lock.json
index fbd0207e..93d0f8c4 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -10,7 +10,7 @@
       "license": "MIT",
       "dependencies": {
         "moment-of-symmetry": "^0.8.1",
-        "xen-dev-utils": "^0.9.0"
+        "xen-dev-utils": "github:xenharmonic-devs/xen-dev-utils#fix-decimal-fracs"
       },
       "bin": {
         "sonic-weave": "bin/sonic-weave.js"
@@ -4493,8 +4493,8 @@
     },
     "node_modules/xen-dev-utils": {
       "version": "0.9.0",
-      "resolved": "https://registry.npmjs.org/xen-dev-utils/-/xen-dev-utils-0.9.0.tgz",
-      "integrity": "sha512-JsbXSg1zXaBoiKI19p2jC8Ka22YADQsTBD7fc2FkVxLWSdCO5BCS5KcRquDP5vP6J9v8t3B14G/7GZ5DC73rzg==",
+      "resolved": "git+ssh://git@github.com/xenharmonic-devs/xen-dev-utils.git#ee7b651f8fe4477ca003251243b508fec4210131",
+      "license": "MIT",
       "engines": {
         "node": ">=10.6.0"
       },
diff --git a/package.json b/package.json
index 40a670dd..a5bf525d 100644
--- a/package.json
+++ b/package.json
@@ -68,7 +68,7 @@
   },
   "dependencies": {
     "moment-of-symmetry": "^0.8.1",
-    "xen-dev-utils": "^0.9.0"
+    "xen-dev-utils": "github:xenharmonic-devs/xen-dev-utils#fix-decimal-fracs"
   },
   "engines": {
     "node": ">=12.0.0"
diff --git a/src/monzo.ts b/src/monzo.ts
index d650ba05..e7ac7b4d 100644
--- a/src/monzo.ts
+++ b/src/monzo.ts
@@ -1827,7 +1827,14 @@ export class TimeMonzo {
     }
     const vector = [];
     for (let i = 0; i < other.primeExponents.length; ++i) {
-      vector.push(this.primeExponents[i].add(other.primeExponents[i]));
+      try {
+        vector.push(this.primeExponents[i].add(other.primeExponents[i]));
+      } catch {
+        return new TimeReal(
+          this.timeExponent.valueOf() + other.timeExponent.valueOf(),
+          this.valueOf() * other.valueOf()
+        );
+      }
     }
     try {
       const residual = this.residual.mul(other.residual);
diff --git a/src/parser/__tests__/expression.spec.ts b/src/parser/__tests__/expression.spec.ts
index 838a8b84..f14da1da 100644
--- a/src/parser/__tests__/expression.spec.ts
+++ b/src/parser/__tests__/expression.spec.ts
@@ -2409,6 +2409,18 @@ describe('SonicWeave expression evaluator', () => {
     const {interval} = parseSingle(String.raw`\\\P1 tmpr 12@`);
     expect(interval.totalCents()).toBe(-1500);
   });
+
+  it('coerces too accurate cents too real', () => {
+    const interval = evaluate('1234.56789012345678901') as Interval;
+    expect(interval.value).toBeInstanceOf(TimeReal);
+    expect(interval.valueOf()).toBeCloseTo(2.04);
+  });
+
+  it('coerces too accurate monzos to real', () => {
+    const ronzo = evaluate('[1.234567890123456780901>') as Interval;
+    expect(ronzo.value).toBeInstanceOf(TimeReal);
+    expect(ronzo.valueOf()).toBeCloseTo(2.3531);
+  });
 });
 
 describe('Poor grammar / Fun with "<"', () => {
diff --git a/src/parser/__tests__/source.spec.ts b/src/parser/__tests__/source.spec.ts
index 12e8fb7f..c860ce09 100644
--- a/src/parser/__tests__/source.spec.ts
+++ b/src/parser/__tests__/source.spec.ts
@@ -1991,4 +1991,34 @@ describe('SonicWeave parser', () => {
       'Index out of range.'
     );
   });
+
+  it('can handle too complex multiplication resulting from too accurate prime mappings', () => {
+    const scale = expand(`
+      14/13
+      8/7
+      44/35
+      4/3
+      99/70
+      99/65
+      396/245
+      2178/1225
+      66/35
+      9801/4900
+      (* Commas = 1716/1715, 2080/2079 *)
+      PrimeMapping(1200., 1902.0236738027506, 2786.2942222449124, 3369.11433503606, 4151.361209675464, 4440.252343874884)
+      cents(£, 3)
+    `);
+    expect(scale).toEqual([
+      '128.862',
+      '230.886',
+      '395.953',
+      '497.976',
+      '600.',
+      '728.862',
+      '830.886',
+      '995.953',
+      '1097.976',
+      '1200.',
+    ]);
+  });
 });
diff --git a/src/parser/expression.ts b/src/parser/expression.ts
index 9a7c633f..bcee1825 100644
--- a/src/parser/expression.ts
+++ b/src/parser/expression.ts
@@ -1,4 +1,4 @@
-import {Fraction, gcd} from 'xen-dev-utils';
+import {Fraction, PRIMES, gcd} from 'xen-dev-utils';
 import {
   NedjiLiteral,
   IntegerLiteral,
@@ -662,7 +662,18 @@ export class ExpressionVisitor {
 
   protected visitComponent(component: VectorComponent) {
     // XXX: This is so backwards...
-    return new Fraction(formatComponent(component));
+    const str = formatComponent(component);
+    try {
+      return new Fraction(str);
+    } catch {
+      if (component.separator === '/') {
+        return (
+          (component.left / parseInt(component.right)) *
+          10 ** (component.exponent ?? 0)
+        );
+      }
+      return parseFloat(str);
+    }
   }
 
   protected upLift(
@@ -703,7 +714,21 @@ export class ExpressionVisitor {
         }
       }
     } else {
-      value = new TimeMonzo(ZERO, exponents);
+      let valid = true;
+      for (const exponent of exponents) {
+        if (typeof exponent === 'number') {
+          valid = false;
+        }
+      }
+      if (valid) {
+        value = new TimeMonzo(ZERO, exponents as Fraction[]);
+      } else {
+        let num = 1;
+        for (let i = 0; i < exponents.length; ++i) {
+          num *= PRIMES[i] ** exponents[i].valueOf();
+        }
+        value = new TimeReal(0, num);
+      }
     }
     const result = this.upLift(value, node);
     if (steps.d !== 1) {
@@ -719,6 +744,11 @@ export class ExpressionVisitor {
 
   protected visitValLiteral(node: ValLiteral) {
     const val = node.components.map(this.visitComponent);
+    for (const component of val) {
+      if (typeof component === 'number') {
+        throw new Error('Invalid val literal.');
+      }
+    }
     let value: TimeMonzo;
     let equave = TWO_MONZO;
     if (node.basis.length) {
@@ -729,7 +759,7 @@ export class ExpressionVisitor {
       value = valToTimeMonzo(val, subgroup);
       equave = subgroup[0];
     } else {
-      value = new TimeMonzo(ZERO, val);
+      value = new TimeMonzo(ZERO, val as Fraction[]);
     }
     return new Val(value, equave, node);
   }