diff --git a/lib/std/math/big/int.zig b/lib/std/math/big/int.zig
index 9f22de9aa3..0f8ca0f3bb 100644
--- a/lib/std/math/big/int.zig
+++ b/lib/std/math/big/int.zig
@@ -2780,7 +2780,7 @@ pub const Managed = struct {
         if (alias_count == 0) {
             m.mulNoAlias(a.toConst(), b.toConst(), rma.allocator);
         } else {
-            const limb_count = calcMulLimbsBufferLen(a.limbs.len, b.limbs.len, alias_count);
+            const limb_count = calcMulLimbsBufferLen(a.toConst().limbs.len, b.toConst().limbs.len, alias_count);
             const limbs_buffer = try rma.allocator.alloc(Limb, limb_count);
             defer rma.allocator.free(limbs_buffer);
             m.mul(a.toConst(), b.toConst(), limbs_buffer, rma.allocator);
@@ -2960,7 +2960,7 @@ pub const Managed = struct {
 
     /// r = a * a
     pub fn sqr(rma: *Managed, a: *const Managed) !void {
-        const needed_limbs = 2 * a.limbs.len + 1;
+        const needed_limbs = 2 * a.toConst().limbs.len + 1;
 
         if (rma.limbs.ptr == a.limbs.ptr) {
             var m = try Managed.initCapacity(rma.allocator, needed_limbs);
diff --git a/lib/std/math/big/int_test.zig b/lib/std/math/big/int_test.zig
index efd5c487d8..5b51106ca4 100644
--- a/lib/std/math/big/int_test.zig
+++ b/lib/std/math/big/int_test.zig
@@ -2883,3 +2883,35 @@ test "big int byte swap" {
     try byteSwapTest(i32, 0x123456f8, @bitCast(i32, @as(u32, 0xf8563412)));
     try byteSwapTest(i48, 0x123456789abc, @bitCast(i48, @as(u48, 0xbc9a78563412)));
 }
+
+test "big.int mul multi-multi alias r with a and b" {
+    var a = try Managed.initSet(testing.allocator, 2 * maxInt(Limb));
+    defer a.deinit();
+
+    try a.mul(&a, &a);
+
+    var want = try Managed.initSet(testing.allocator, 4 * maxInt(Limb) * maxInt(Limb));
+    defer want.deinit();
+
+    try testing.expect(a.eq(want));
+
+    if (@typeInfo(Limb).Int.bits == 64) {
+        try testing.expectEqual(@as(usize, 5), a.limbs.len);
+    }
+}
+
+test "big.int sqr multi alias r with a" {
+    var a = try Managed.initSet(testing.allocator, 2 * maxInt(Limb));
+    defer a.deinit();
+
+    try a.sqr(&a);
+
+    var want = try Managed.initSet(testing.allocator, 4 * maxInt(Limb) * maxInt(Limb));
+    defer want.deinit();
+
+    try testing.expect(a.eq(want));
+
+    if (@typeInfo(Limb).Int.bits == 64) {
+        try testing.expectEqual(@as(usize, 5), a.limbs.len);
+    }
+}