diff --git a/package-lock.json b/package-lock.json
index 2f8467bb..d4acdadb 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -3251,7 +3251,8 @@
       "license": "(GPL-3.0 OR Apache-2.0)",
       "dependencies": {
         "math-expressions-rs-wasm": "*",
-        "mathjs": "^15.2.0"
+        "mathjs": "^15.2.0",
+        "numeric": "1.2.6"
       },
       "devDependencies": {
         "underscore": "^1.13.6",
diff --git a/packages/math-expressions-js-compat/lib/mathjs.ts b/packages/math-expressions-js-compat/lib/mathjs.ts
index 602400a4..3fbbc2c4 100644
--- a/packages/math-expressions-js-compat/lib/mathjs.ts
+++ b/packages/math-expressions-js-compat/lib/mathjs.ts
@@ -2,7 +2,31 @@
 // as `me.math` / `../lib/mathjs`. We re-export the npm `mathjs` default so specs
 // that reach for it keep working.
 import * as mathjs from "mathjs";
+import numeric from "numeric";
 
 const math = mathjs.create ? mathjs.create(mathjs.all) : mathjs;
 
+// The original `me.math` carried numeric.js's functions alongside math.js's, and
+// consumers reach for the ones math.js has no equivalent of: DoenetML's
+// `<odeSystem>` integrates with `me.math.dopri`. Keep importing them, or this
+// drop-in silently drops those names. `silent` skips the ones math.js already
+// defines, leaving math.js's own implementations in place.
+(math as mathjs.MathJsInstance).import(numeric, { wrap: true, silent: true });
+
+// numeric.js builds most of its helpers at load time with the `Function`
+// constructor, and the generated bodies reference a bare `numeric` (e.g.
+// `_s = numeric.dim(x)`). Functions made that way are evaluated in global scope,
+// so the reference resolves only if `numeric` is a property of the global
+// object. numeric.js puts it there itself, but only through `global`, which
+// exists in Node and nowhere else — so in a browser or a web worker every
+// generated helper throws `ReferenceError: numeric is not defined` the first
+// time it is called, `dopri` included. Publish it ourselves to cover every
+// runtime.
+//
+// Assigned unconditionally rather than guarded on `globalThis.numeric ===
+// undefined`: on a page holding an element whose id is `numeric`, the
+// named-element global makes the slot look occupied while still being useless
+// to the generated code.
+(globalThis as Record<string, unknown>).numeric = numeric;
+
 export default math;
diff --git a/packages/math-expressions-js-compat/package.json b/packages/math-expressions-js-compat/package.json
index 06d9aced..217fb6f9 100644
--- a/packages/math-expressions-js-compat/package.json
+++ b/packages/math-expressions-js-compat/package.json
@@ -23,7 +23,8 @@
   },
   "dependencies": {
     "math-expressions-rs-wasm": "*",
-    "mathjs": "^15.2.0"
+    "mathjs": "^15.2.0",
+    "numeric": "1.2.6"
   },
   "devDependencies": {
     "underscore": "^1.13.6",
diff --git a/packages/math-expressions-js-compat/spec/quick_mathjs-numeric.spec.ts b/packages/math-expressions-js-compat/spec/quick_mathjs-numeric.spec.ts
new file mode 100644
index 00000000..a3a13dfd
--- /dev/null
+++ b/packages/math-expressions-js-compat/spec/quick_mathjs-numeric.spec.ts
@@ -0,0 +1,64 @@
+// `me.math` in the original library was math.js *plus* numeric.js, and callers
+// reach for names only numeric provides — DoenetML's `<odeSystem>` integrates
+// with `me.math.dopri`. This covers that the drop-in still carries them, and
+// that they work outside Node.
+//
+// numeric.js builds most of its helpers at load time with the `Function`
+// constructor, and the generated bodies reference a bare `numeric`, which
+// resolves only against the global object. numeric.js registers itself there
+// through Node's `global`; under Node that would happen with or without
+// `lib/mathjs` doing it too, so `global` is deleted before the first import of
+// the module — reproducing the shape a browser or a web worker sees.
+//
+// Hence no static import of `../lib/mathjs` here: it has to load *after* the
+// deletion, inside the test.
+
+type Dopri = (
+  t0: number,
+  t1: number,
+  x0: number[],
+  f: (t: number, x: number[]) => number[],
+  tolerance: number,
+  maxIterations: number,
+) => { at: (t: number) => number[] };
+
+describe("numeric functions on me.math", function () {
+  let hadGlobal: boolean, savedGlobal: unknown;
+  let hadNumeric: boolean, savedNumeric: unknown;
+
+  beforeEach(function () {
+    hadGlobal = "global" in globalThis;
+    savedGlobal = (globalThis as Record<string, unknown>).global;
+    hadNumeric = "numeric" in globalThis;
+    savedNumeric = (globalThis as Record<string, unknown>).numeric;
+  });
+
+  afterEach(function () {
+    const g = globalThis as Record<string, unknown>;
+    if (hadGlobal) g.global = savedGlobal;
+    else delete g.global;
+    if (hadNumeric) g.numeric = savedNumeric;
+    else delete g.numeric;
+  });
+
+  it("keeps the names math.js has no equivalent of, with no `global`", async function () {
+    const g = globalThis as Record<string, unknown>;
+    delete g.global;
+    delete g.numeric;
+
+    const { default: math } = await import("../lib/mathjs");
+
+    // The registration `lib/mathjs` makes on numeric's behalf.
+    expect(typeof g.numeric).toBe("object");
+    expect(typeof (g.numeric as Record<string, unknown>).dim).toBe("function");
+
+    // `dopri` has no math.js equivalent, and it reaches numeric's generated
+    // `add`/`mul`/`sub` helpers — so it throws `ReferenceError: numeric is not
+    // defined` without that registration. x' = x from x(0) = 1 integrates to e.
+    // Cast because it comes from numeric, so math.js's types do not name it.
+    const { dopri } = math as unknown as { dopri: Dopri };
+    expect(typeof dopri).toBe("function");
+    const solution = dopri(0, 1, [1], (t, x) => [x[0]], 1e-6, 1000);
+    expect(solution.at(1)[0]).toBeCloseTo(Math.E, 5);
+  });
+});