diff --git a/release/c/wuffs-unsupported-snapshot.c b/release/c/wuffs-unsupported-snapshot.c
index 9aadd1a..fe922b0 100644
--- a/release/c/wuffs-unsupported-snapshot.c
+++ b/release/c/wuffs-unsupported-snapshot.c
@@ -6022,6 +6022,7 @@
 
     uint32_t p_decode_tokens[1];
     uint32_t p_decode_leading[1];
+    uint32_t p_decode_comment[1];
     uint32_t p_decode_trailing_new_line[1];
   } private_impl;
 
@@ -6033,6 +6034,9 @@
       uint32_t v_expect;
       uint32_t v_expect_after_value;
     } s_decode_tokens[1];
+    struct {
+      uint32_t v_link_prev;
+    } s_decode_comment[1];
   } private_data;
 
 #ifdef __cplusplus
@@ -20367,6 +20371,11 @@
                                     wuffs_base__io_buffer* a_src);
 
 static wuffs_base__status  //
+wuffs_json__decoder__decode_comment(wuffs_json__decoder* self,
+                                    wuffs_base__token_buffer* a_dst,
+                                    wuffs_base__io_buffer* a_src);
+
+static wuffs_base__status  //
 wuffs_json__decoder__decode_trailing_new_line(wuffs_json__decoder* self,
                                               wuffs_base__token_buffer* a_dst,
                                               wuffs_base__io_buffer* a_src);
@@ -21549,6 +21558,28 @@
             WUFFS_BASE__COROUTINE_SUSPENSION_POINT_MAYBE_SUSPEND(20);
             goto label__outer__continue;
           }
+        } else if (v_class == 12) {
+          if (self->private_impl.f_quirk_enabled_allow_comment_block ||
+              self->private_impl.f_quirk_enabled_allow_comment_line) {
+            if (a_dst) {
+              a_dst->meta.wi = ((size_t)(iop_a_dst - a_dst->data.ptr));
+            }
+            if (a_src) {
+              a_src->meta.ri = ((size_t)(iop_a_src - a_src->data.ptr));
+            }
+            WUFFS_BASE__COROUTINE_SUSPENSION_POINT(21);
+            status = wuffs_json__decoder__decode_comment(self, a_dst, a_src);
+            if (a_dst) {
+              iop_a_dst = a_dst->data.ptr + a_dst->meta.wi;
+            }
+            if (a_src) {
+              iop_a_src = a_src->data.ptr + a_src->meta.ri;
+            }
+            if (status.repr) {
+              goto suspend;
+            }
+            goto label__outer__continue;
+          }
         }
         status = wuffs_base__make_status(wuffs_json__error__bad_input);
         goto exit;
@@ -21567,7 +21598,7 @@
       if (a_src) {
         a_src->meta.ri = ((size_t)(iop_a_src - a_src->data.ptr));
       }
-      WUFFS_BASE__COROUTINE_SUSPENSION_POINT(21);
+      WUFFS_BASE__COROUTINE_SUSPENSION_POINT(22);
       status =
           wuffs_json__decoder__decode_trailing_new_line(self, a_dst, a_src);
       if (a_dst) {
@@ -21913,6 +21944,209 @@
   return status;
 }
 
+// -------- func json.decoder.decode_comment
+
+static wuffs_base__status  //
+wuffs_json__decoder__decode_comment(wuffs_json__decoder* self,
+                                    wuffs_base__token_buffer* a_dst,
+                                    wuffs_base__io_buffer* a_src) {
+  wuffs_base__status status = wuffs_base__make_status(NULL);
+
+  uint8_t v_c8 = 0;
+  uint16_t v_c16 = 0;
+  uint32_t v_link_prev = 0;
+  uint32_t v_length = 0;
+
+  wuffs_base__token* iop_a_dst = NULL;
+  wuffs_base__token* io0_a_dst WUFFS_BASE__POTENTIALLY_UNUSED = NULL;
+  wuffs_base__token* io1_a_dst WUFFS_BASE__POTENTIALLY_UNUSED = NULL;
+  wuffs_base__token* io2_a_dst WUFFS_BASE__POTENTIALLY_UNUSED = NULL;
+  if (a_dst) {
+    io0_a_dst = a_dst->data.ptr;
+    io1_a_dst = io0_a_dst + a_dst->meta.wi;
+    iop_a_dst = io1_a_dst;
+    io2_a_dst = io0_a_dst + a_dst->data.len;
+    if (a_dst->meta.closed) {
+      io2_a_dst = iop_a_dst;
+    }
+  }
+  uint8_t* iop_a_src = NULL;
+  uint8_t* io0_a_src WUFFS_BASE__POTENTIALLY_UNUSED = NULL;
+  uint8_t* io1_a_src WUFFS_BASE__POTENTIALLY_UNUSED = NULL;
+  uint8_t* io2_a_src WUFFS_BASE__POTENTIALLY_UNUSED = NULL;
+  if (a_src) {
+    io0_a_src = a_src->data.ptr;
+    io1_a_src = io0_a_src + a_src->meta.ri;
+    iop_a_src = io1_a_src;
+    io2_a_src = io0_a_src + a_src->meta.wi;
+  }
+
+  uint32_t coro_susp_point = self->private_impl.p_decode_comment[0];
+  if (coro_susp_point) {
+    v_link_prev = self->private_data.s_decode_comment[0].v_link_prev;
+  }
+  switch (coro_susp_point) {
+    WUFFS_BASE__COROUTINE_SUSPENSION_POINT_0;
+
+  label__0__continue:;
+    while ((((uint64_t)(io2_a_dst - iop_a_dst)) <= 0) ||
+           (((uint64_t)(io2_a_src - iop_a_src)) <= 1)) {
+      if (((uint64_t)(io2_a_dst - iop_a_dst)) <= 0) {
+        status = wuffs_base__make_status(wuffs_base__suspension__short_write);
+        WUFFS_BASE__COROUTINE_SUSPENSION_POINT_MAYBE_SUSPEND(1);
+        goto label__0__continue;
+      }
+      if (a_src && a_src->meta.closed) {
+        status = wuffs_base__make_status(wuffs_json__error__bad_input);
+        goto exit;
+      }
+      status = wuffs_base__make_status(wuffs_base__suspension__short_read);
+      WUFFS_BASE__COROUTINE_SUSPENSION_POINT_MAYBE_SUSPEND(2);
+    }
+    v_c16 = wuffs_base__load_u16le__no_bounds_check(iop_a_src);
+    if ((v_c16 == 10799) &&
+        self->private_impl.f_quirk_enabled_allow_comment_block) {
+      (iop_a_src += 2, wuffs_base__make_empty_struct());
+      v_length = 2;
+    label__comment_block__continue:;
+      while (true) {
+        if (((uint64_t)(io2_a_dst - iop_a_dst)) <= 0) {
+          status = wuffs_base__make_status(wuffs_base__suspension__short_write);
+          WUFFS_BASE__COROUTINE_SUSPENSION_POINT_MAYBE_SUSPEND(3);
+          v_length = 0;
+          goto label__comment_block__continue;
+        }
+        while (true) {
+          if (((uint64_t)(io2_a_src - iop_a_src)) <= 1) {
+            if (v_length > 0) {
+              *iop_a_dst++ = wuffs_base__make_token(
+                  (((uint64_t)(2)) << WUFFS_BASE__TOKEN__VALUE_MINOR__SHIFT) |
+                  (((uint64_t)((1 | v_link_prev)))
+                   << WUFFS_BASE__TOKEN__LINK__SHIFT) |
+                  (((uint64_t)(v_length)) << WUFFS_BASE__TOKEN__LENGTH__SHIFT));
+              v_link_prev = 2;
+            }
+            if (a_src && a_src->meta.closed) {
+              status = wuffs_base__make_status(wuffs_json__error__bad_input);
+              goto exit;
+            }
+            status =
+                wuffs_base__make_status(wuffs_base__suspension__short_read);
+            WUFFS_BASE__COROUTINE_SUSPENSION_POINT_MAYBE_SUSPEND(4);
+            v_length = 0;
+            goto label__comment_block__continue;
+          }
+          v_c16 = wuffs_base__load_u16le__no_bounds_check(iop_a_src);
+          if (v_c16 == 12074) {
+            (iop_a_src += 2, wuffs_base__make_empty_struct());
+            *iop_a_dst++ = wuffs_base__make_token(
+                (((uint64_t)(2)) << WUFFS_BASE__TOKEN__VALUE_MINOR__SHIFT) |
+                (((uint64_t)(v_link_prev)) << WUFFS_BASE__TOKEN__LINK__SHIFT) |
+                (((uint64_t)((v_length + 2)))
+                 << WUFFS_BASE__TOKEN__LENGTH__SHIFT));
+            status = wuffs_base__make_status(NULL);
+            goto ok;
+          }
+          (iop_a_src += 1, wuffs_base__make_empty_struct());
+          if (v_length >= 65533) {
+            *iop_a_dst++ = wuffs_base__make_token(
+                (((uint64_t)(2)) << WUFFS_BASE__TOKEN__VALUE_MINOR__SHIFT) |
+                (((uint64_t)((1 | v_link_prev)))
+                 << WUFFS_BASE__TOKEN__LINK__SHIFT) |
+                (((uint64_t)((v_length + 1)))
+                 << WUFFS_BASE__TOKEN__LENGTH__SHIFT));
+            v_length = 0;
+            v_link_prev = 2;
+            goto label__comment_block__continue;
+          }
+          v_length += 1;
+        }
+      }
+    } else if ((v_c16 == 12079) &&
+               self->private_impl.f_quirk_enabled_allow_comment_line) {
+      (iop_a_src += 2, wuffs_base__make_empty_struct());
+      v_length = 2;
+    label__comment_line__continue:;
+      while (true) {
+        if (((uint64_t)(io2_a_dst - iop_a_dst)) <= 0) {
+          status = wuffs_base__make_status(wuffs_base__suspension__short_write);
+          WUFFS_BASE__COROUTINE_SUSPENSION_POINT_MAYBE_SUSPEND(5);
+          v_length = 0;
+          goto label__comment_line__continue;
+        }
+        while (true) {
+          if (((uint64_t)(io2_a_src - iop_a_src)) <= 0) {
+            if (v_length > 0) {
+              *iop_a_dst++ = wuffs_base__make_token(
+                  (((uint64_t)(1)) << WUFFS_BASE__TOKEN__VALUE_MINOR__SHIFT) |
+                  (((uint64_t)((1 | v_link_prev)))
+                   << WUFFS_BASE__TOKEN__LINK__SHIFT) |
+                  (((uint64_t)(v_length)) << WUFFS_BASE__TOKEN__LENGTH__SHIFT));
+              v_link_prev = 2;
+            }
+            if (a_src && a_src->meta.closed) {
+              status = wuffs_base__make_status(wuffs_json__error__bad_input);
+              goto exit;
+            }
+            status =
+                wuffs_base__make_status(wuffs_base__suspension__short_read);
+            WUFFS_BASE__COROUTINE_SUSPENSION_POINT_MAYBE_SUSPEND(6);
+            v_length = 0;
+            goto label__comment_line__continue;
+          }
+          v_c8 = wuffs_base__load_u8be__no_bounds_check(iop_a_src);
+          if (v_c8 == 10) {
+            (iop_a_src += 1, wuffs_base__make_empty_struct());
+            *iop_a_dst++ = wuffs_base__make_token(
+                (((uint64_t)(1)) << WUFFS_BASE__TOKEN__VALUE_MINOR__SHIFT) |
+                (((uint64_t)(v_link_prev)) << WUFFS_BASE__TOKEN__LINK__SHIFT) |
+                (((uint64_t)((v_length + 1)))
+                 << WUFFS_BASE__TOKEN__LENGTH__SHIFT));
+            status = wuffs_base__make_status(NULL);
+            goto ok;
+          }
+          (iop_a_src += 1, wuffs_base__make_empty_struct());
+          if (v_length >= 65533) {
+            *iop_a_dst++ = wuffs_base__make_token(
+                (((uint64_t)(1)) << WUFFS_BASE__TOKEN__VALUE_MINOR__SHIFT) |
+                (((uint64_t)((1 | v_link_prev)))
+                 << WUFFS_BASE__TOKEN__LINK__SHIFT) |
+                (((uint64_t)((v_length + 1)))
+                 << WUFFS_BASE__TOKEN__LENGTH__SHIFT));
+            v_length = 0;
+            v_link_prev = 2;
+            goto label__comment_line__continue;
+          }
+          v_length += 1;
+        }
+      }
+    }
+    status = wuffs_base__make_status(wuffs_json__error__bad_input);
+    goto exit;
+    goto ok;
+  ok:
+    self->private_impl.p_decode_comment[0] = 0;
+    goto exit;
+  }
+
+  goto suspend;
+suspend:
+  self->private_impl.p_decode_comment[0] =
+      wuffs_base__status__is_suspension(&status) ? coro_susp_point : 0;
+  self->private_data.s_decode_comment[0].v_link_prev = v_link_prev;
+
+  goto exit;
+exit:
+  if (a_dst) {
+    a_dst->meta.wi = ((size_t)(iop_a_dst - a_dst->data.ptr));
+  }
+  if (a_src) {
+    a_src->meta.ri = ((size_t)(iop_a_src - a_src->data.ptr));
+  }
+
+  return status;
+}
+
 // -------- func json.decoder.decode_trailing_new_line
 
 static wuffs_base__status  //
diff --git a/std/json/decode_json.wuffs b/std/json/decode_json.wuffs
index e297898..176fd09 100644
--- a/std/json/decode_json.wuffs
+++ b/std/json/decode_json.wuffs
@@ -1070,6 +1070,12 @@
 					yield? base."$short read"
 					continue.outer
 				}
+
+			} else if class == 0x0C {  // 0x0C is CLASS_COMMENT.
+				if this.quirk_enabled_allow_comment_block or this.quirk_enabled_allow_comment_line {
+					this.decode_comment?(dst: args.dst, src: args.src)
+					continue.outer
+				}
 			}
 
 			return "#bad input"
@@ -1310,6 +1316,145 @@
 	}
 }
 
+pri func decoder.decode_comment?(dst: base.token_writer, src: base.io_reader) {
+	var c8        : base.u8
+	var c16       : base.u16
+	var link_prev : base.u32[..= 0x2]
+	var length    : base.u32[..= 0xFFFD]
+
+	while (args.dst.available() <= 0) or (args.src.available() <= 1),
+		post args.dst.available() > 0,
+		post args.src.available() > 1,
+	{
+		if args.dst.available() <= 0 {
+			yield? base."$short write"
+			continue
+		}
+		if args.src.is_closed() {
+			return "#bad input"
+		}
+		yield? base."$short read"
+	}
+	c16 = args.src.peek_u16le()
+
+	if (c16 == 0x2A2F) and this.quirk_enabled_allow_comment_block {
+		args.src.skip32_fast!(actual: 2, worst_case: 2)
+		length = 2
+
+		while.comment_block true {
+			if args.dst.available() <= 0 {
+				yield? base."$short write"
+				length = 0
+				continue.comment_block
+			}
+
+			while true,
+				pre args.dst.available() > 0,
+			{
+				if args.src.available() <= 1 {
+					if length > 0 {
+						args.dst.write_fast_token!(
+							value_major: 0,
+							value_minor: 0x2,
+							link: 0x1 | link_prev,
+							length: length)
+						link_prev = 0x2
+					}
+					if args.src.is_closed() {
+						return "#bad input"
+					}
+					yield? base."$short read"
+					length = 0
+					continue.comment_block
+				}
+
+				c16 = args.src.peek_u16le()
+				if c16 == 0x2F2A {  // 0x2F2A is "*/" little-endian.
+					args.src.skip32_fast!(actual: 2, worst_case: 2)
+					args.dst.write_fast_token!(
+						value_major: 0,
+						value_minor: 0x2,
+						link: link_prev,
+						length: length + 2)
+					return ok
+				}
+
+				args.src.skip32_fast!(actual: 1, worst_case: 1)
+				if length >= 0xFFFD {
+					args.dst.write_fast_token!(
+						value_major: 0,
+						value_minor: 0x2,
+						link: 0x1 | link_prev,
+						length: length + 1)
+					length = 0
+					link_prev = 0x2
+					continue.comment_block
+				}
+				length += 1
+			}
+		} endwhile.comment_block
+
+	} else if (c16 == 0x2F2F) and this.quirk_enabled_allow_comment_line {
+		args.src.skip32_fast!(actual: 2, worst_case: 2)
+		length = 2
+
+		while.comment_line true {
+			if args.dst.available() <= 0 {
+				yield? base."$short write"
+				length = 0
+				continue.comment_line
+			}
+
+			while true,
+				pre args.dst.available() > 0,
+			{
+				if args.src.available() <= 0 {
+					if length > 0 {
+						args.dst.write_fast_token!(
+							value_major: 0,
+							value_minor: 0x1,
+							link: 0x1 | link_prev,
+							length: length)
+						link_prev = 0x2
+					}
+					if args.src.is_closed() {
+						return "#bad input"
+					}
+					yield? base."$short read"
+					length = 0
+					continue.comment_line
+				}
+
+				c8 = args.src.peek_u8()
+				if c8 == 0x0A {  // 0x0A is '\n'.
+					args.src.skip32_fast!(actual: 1, worst_case: 1)
+					args.dst.write_fast_token!(
+						value_major: 0,
+						value_minor: 0x1,
+						link: link_prev,
+						length: length + 1)
+					return ok
+				}
+
+				args.src.skip32_fast!(actual: 1, worst_case: 1)
+				if length >= 0xFFFD {
+					args.dst.write_fast_token!(
+						value_major: 0,
+						value_minor: 0x1,
+						link: 0x1 | link_prev,
+						length: length + 1)
+					length = 0
+					link_prev = 0x2
+					continue.comment_line
+				}
+				length += 1
+			}
+		} endwhile.comment_line
+	}
+
+	return "#bad input"
+}
+
 pri func decoder.decode_trailing_new_line?(dst: base.token_writer, src: base.io_reader) {
 	var c                 : base.u8
 	var whitespace_length : base.u32[..= 0xFFFE]
diff --git a/std/json/decode_quirks.wuffs b/std/json/decode_quirks.wuffs
index 4daf310..c2bda1a 100644
--- a/std/json/decode_quirks.wuffs
+++ b/std/json/decode_quirks.wuffs
@@ -68,18 +68,23 @@
 // anywhere whitespace would be, although see the quirk_allow_trailing_new_line
 // comment for additional interaction when combining multiple quirks.
 //
-// They produce WUFFS_BASE__TOKEN__VBD__FILLER__COMMENT_BLOCK tokens.
+// They produce WUFFS_BASE__TOKEN__VBD__FILLER__COMMENT_BLOCK tokens. The token
+// chain's source bytes includes the starting "/*" and the ending "*/".
 pub const quirk_allow_comment_block base.u32 = 0x4909_9400 | 0x08
 
 // When this quirk is enabled, "// C/C++ style line comments\n" are accepted
 // anywhere whitespace would be, although see the quirk_allow_trailing_new_line
 // comment for additional interaction when combining multiple quirks.
 //
-// A line comment may omit the trailing '\n' if there is no input afterwards
-// (i.e. the line comment ends with the end-of-file), but note the
-// quirk_allow_trailing_new_line interaction already mentioned.
+// A line comment may not omit the ending "\n", even if there is no input
+// afterwards (i.e. the prospective line comment ends with the end-of-file).
 //
-// They produce WUFFS_BASE__TOKEN__VBD__FILLER__COMMENT_LINE tokens.
+// They produce WUFFS_BASE__TOKEN__VBD__FILLER__COMMENT_LINE tokens. The token
+// chain's source bytes includes the starting "//" and the ending "\n".
+//
+// Even if the line comments are on consecutive lines, each line comment is a
+// separate token chain. There may be whitespace tokens between one line
+// comment's ending "\n" and the next one's starting "//".
 pub const quirk_allow_comment_line base.u32 = 0x4909_9400 | 0x09
 
 // When this quirk is enabled, there may be a comma after the final array
diff --git a/test/c/std/json.c b/test/c/std/json.c
index 2d9cb1e..e345344 100644
--- a/test/c/std/json.c
+++ b/test/c/std/json.c
@@ -1330,6 +1330,78 @@
 }
 
 const char*  //
+test_wuffs_json_decode_quirk_allow_comment_etc() {
+  CHECK_FOCUS(__func__);
+
+  struct {
+    // want has 4 bytes, one for each possible q:
+    //  - q&1 sets WUFFS_JSON__QUIRK_ALLOW_COMMENT_BLOCK.
+    //  - q&2 sets WUFFS_JSON__QUIRK_ALLOW_COMMENT_LINE.
+    // An 'X', '+' or '-' means that decoding should succeed (and consume the
+    // entire input), succeed (without consuming the entire input) or fail.
+    const char* want;
+    const char* str;
+  } test_cases[] = {
+      {.want = "-X-X", .str = "[ /*com*/ 0]"},
+      {.want = "--XX", .str = "//l\n  //m\n0"},
+      {.want = "---X", .str = "[ 0, /*com*/ 1 //l\n\n]"},
+      {.want = "----", .str = "/*/0"},   // Not a valid slash-star comment.
+      {.want = "----", .str = "[4/5]"},  // Lone slash.
+  };
+
+  int tc;
+  for (tc = 0; tc < WUFFS_TESTLIB_ARRAY_SIZE(test_cases); tc++) {
+    int q;
+    for (q = 0; q < 4; q++) {
+      wuffs_json__decoder dec;
+      CHECK_STATUS("initialize", wuffs_json__decoder__initialize(
+                                     &dec, sizeof dec, WUFFS_VERSION,
+                                     WUFFS_INITIALIZE__DEFAULT_OPTIONS));
+      wuffs_json__decoder__set_quirk_enabled(
+          &dec, WUFFS_JSON__QUIRK_ALLOW_COMMENT_BLOCK, q & 1);
+      wuffs_json__decoder__set_quirk_enabled(
+          &dec, WUFFS_JSON__QUIRK_ALLOW_COMMENT_LINE, q & 2);
+
+      wuffs_base__token_buffer tok =
+          wuffs_base__make_token_buffer_writer(global_have_token_slice);
+      wuffs_base__io_buffer src = wuffs_base__make_io_buffer_reader(
+          wuffs_base__make_slice_u8((void*)(test_cases[tc].str),
+                                    strlen(test_cases[tc].str)),
+          true);
+      const char* have =
+          wuffs_json__decoder__decode_tokens(&dec, &tok, &src).repr;
+      const char* want =
+          (test_cases[tc].want[q] != '-') ? NULL : wuffs_json__error__bad_input;
+      if (have != want) {
+        RETURN_FAIL("tc=%d, q=%d: decode_tokens: have \"%s\", want \"%s\"", tc,
+                    q, have, want);
+      }
+
+      size_t total_length = 0;
+      while (tok.meta.ri < tok.meta.wi) {
+        total_length += wuffs_base__token__length(&tok.data.ptr[tok.meta.ri++]);
+      }
+      if (total_length != src.meta.ri) {
+        RETURN_FAIL("tc=%d, q=%d: total_length: have %zu, want %zu", tc, q,
+                    total_length, src.meta.ri);
+      }
+      if (test_cases[tc].want[q] == 'X') {
+        if (total_length != src.data.len) {
+          RETURN_FAIL("tc=%d, q=%d: total_length: have %zu, want %zu", tc, q,
+                      total_length, src.data.len);
+        }
+      } else if (test_cases[tc].want[q] == '+') {
+        if (total_length >= src.data.len) {
+          RETURN_FAIL("tc=%d, q=%d: total_length: have %zu, want < %zu", tc, q,
+                      total_length, src.data.len);
+        }
+      }
+    }
+  }
+  return NULL;
+}
+
+const char*  //
 test_wuffs_json_decode_quirk_allow_leading_etc() {
   CHECK_FOCUS(__func__);
 
@@ -1973,6 +2045,7 @@
     test_wuffs_json_decode_prior_valid_utf_8,
     test_wuffs_json_decode_quirk_allow_backslash_etc,
     test_wuffs_json_decode_quirk_allow_backslash_x,
+    test_wuffs_json_decode_quirk_allow_comment_etc,
     test_wuffs_json_decode_quirk_allow_leading_etc,
     test_wuffs_json_decode_quirk_allow_trailing_etc,
     test_wuffs_json_decode_quirk_replace_invalid_utf_8,