diff --git a/c/types.c b/c/types.c
index d99415c..0e044c8 100644
--- a/c/types.c
+++ b/c/types.c
@@ -419,18 +419,20 @@ Value num_mul(Value a, Value b) {
 }
 
 Value num_div(Value a, Value b) {
-    /* Integer / integer that divides cleanly stays integer (matches Python /
-     * Scheme semantics for `/` between exacts when the quotient is exact).
-     * For bignum case we treat as exact division (truncating to integer when
-     * quotient is exact, else fall back to double for now — secp256k1 ops
-     * never use fractional bignum). */
+    /* Integer / integer that divides cleanly stays integer; otherwise we
+     * promote to an exact rational (matches Python lumbda and R7RS:
+     * `/` between exacts produces an exact result). The previous code
+     * fell back to double for non-divisible int/int — that broke parity
+     * with the Python tier on (/ 67 7), (/ 1 3), etc. */
     if (IS_INTEGER(a) && IS_INTEGER(b)) {
         if (big_is_zero(b)) lisp_error("division by zero");
         Value q = big_quotient(a, b);
         Value r = big_remainder(a, b);
         if (big_is_zero(r)) return q;
-        /* Inexact fallback. */
-        return make_double(as_number_double(a) / as_number_double(b));
+        int64_t an, ad, bn, bd;
+        to_rational(a, &an, &ad);
+        to_rational(b, &bn, &bd);
+        return rational_normalize(an * bd, ad * bn);
     }
     if (is_exact(a) && is_exact(b)) {
         int64_t an, ad, bn, bd;
diff --git a/www/playground/c/lumbda-c.wasm b/www/playground/c/lumbda-c.wasm
index e3aa277..c0835e8 100755
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diff --git a/www/repl/c/lumbda-c.wasm b/www/repl/c/lumbda-c.wasm
index e3aa277..c0835e8 100755
Binary files a/www/repl/c/lumbda-c.wasm and b/www/repl/c/lumbda-c.wasm differ