diff --git a/lib/std/RingBuffer.zig b/lib/std/RingBuffer.zig
index 99f3ff1bc2..f47895ae5b 100644
--- a/lib/std/RingBuffer.zig
+++ b/lib/std/RingBuffer.zig
@@ -74,6 +74,7 @@ pub fn writeSlice(self: *RingBuffer, bytes: []const u8) Error!void {
 /// bytes will be overwritten.
 /// Uses memcpy and so `bytes` must not overlap ring buffer data.
 pub fn writeSliceAssumeCapacity(self: *RingBuffer, bytes: []const u8) void {
+    assert(bytes.len <= self.data.len);
     const data_start = self.mask(self.write_index);
     const part1_data_end = @min(data_start + bytes.len, self.data.len);
     const part1_len = part1_data_end - data_start;
@@ -104,6 +105,7 @@ pub fn writeSliceForwards(self: *RingBuffer, bytes: []const u8) Error!void {
 /// bytes will be overwritten.
 /// Uses copyForwards and can write slices from this RingBuffer into itself.
 pub fn writeSliceForwardsAssumeCapacity(self: *RingBuffer, bytes: []const u8) void {
+    assert(bytes.len <= self.data.len);
     const data_start = self.mask(self.write_index);
     const part1_data_end = @min(data_start + bytes.len, self.data.len);
     const part1_len = part1_data_end - data_start;
@@ -160,6 +162,7 @@ pub fn readFirstAssumeLength(self: *RingBuffer, dest: []u8, length: usize) void
 /// Reads last `length` bytes written to the ring buffer into `dest`; Returns
 /// Error.ReadLengthInvalid if length greater than ring or dest length
 /// Uses memcpy and so `dest` must not overlap ring buffer data.
+/// Reduces write index by `length`.
 pub fn readLast(self: *RingBuffer, dest: []u8, length: usize) Error!void {
     if (length > self.len() or length > dest.len) return error.ReadLengthInvalid;
     self.readLastAssumeLength(dest, length);
@@ -168,6 +171,7 @@ pub fn readLast(self: *RingBuffer, dest: []u8, length: usize) Error!void {
 /// Reads last `length` bytes written to the ring buffer into `dest`;
 /// Asserts that length not greater than ring buffer or dest length
 /// Uses memcpy and so `dest` must not overlap ring buffer data.
+/// Reduces write index by `length`.
 pub fn readLastAssumeLength(self: *RingBuffer, dest: []u8, length: usize) void {
     assert(length <= self.len() and length <= dest.len);
     const data_start = self.mask(self.write_index + self.data.len - length);
@@ -189,7 +193,7 @@ pub fn isFull(self: RingBuffer) bool {
     return self.mask2(self.write_index + self.data.len) == self.read_index;
 }
 
-/// Returns the length
+/// Returns the length of data available for reading
 pub fn len(self: RingBuffer) usize {
     const wrap_offset = 2 * self.data.len * @intFromBool(self.write_index < self.read_index);
     const adjusted_write_index = self.write_index + wrap_offset;