diff --git a/libc/platform/bionic/tls_defines.h b/libc/platform/bionic/tls_defines.h
index 31481c30405062f1be04f6553a6deb1f9ef27edd..c089ea700ee0e937070927ed62dc9a548e1644ca 100644
--- a/libc/platform/bionic/tls_defines.h
+++ b/libc/platform/bionic/tls_defines.h
@@ -116,6 +116,13 @@
 
 #elif (defined(__riscv) && (__riscv_xlen == 64))
 
+// RISC-V ELF Specification[1] specifies that: RISC-V uses Variant I as described
+// by the ELF TLS specification, with tp containing the address one past the end
+// of the TCB.
+//
+// [1]: RISC-V ELF Specification. Section: Thread Local Storage
+// https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-elf.adoc#thread-local-storage
+
 #define MIN_TLS_SLOT             (-9) // update this value when reserving a slot
 
 #define TLS_SLOT_BIONIC_TLS      (-9)
@@ -127,8 +134,6 @@
 #define TLS_SLOT_STACK_GUARD     (-3)
 #define TLS_SLOT_SANITIZER       (-2) // was historically used for dlerror
 #define TLS_SLOT_ART_THREAD_SELF (-1)
-
-// The maximum slot is fixed by the minimum TLS alignment in Bionic executables.
 #define MAX_TLS_SLOT             (-1)
 
 #endif
diff --git a/libc/private/bionic_elf_tls.h b/libc/private/bionic_elf_tls.h
index 6223b3ca9cbe524457406ef531cae2ca5b0b82db..57db3425a364867dfab95f5584e3dbc9f2ee2597 100644
--- a/libc/private/bionic_elf_tls.h
+++ b/libc/private/bionic_elf_tls.h
@@ -203,5 +203,14 @@ void __free_dynamic_tls(bionic_tcb* tcb);
 void __notify_thread_exit_callbacks();
 
 #if (defined(__riscv) && (__riscv_xlen == 64))
+// TLS_DTV_OFFSET is a constant used in relocation fields, defined in RISC-V ELF Specification[1]
+// The front of the TCB contains a pointer to the DTV, and each pointer in DTV
+// points to 0x800 past the start of a TLS block to make full use of the range
+// of load/store instructions, refer to [2].
+//
+// [1]: RISC-V ELF Specification.
+// https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-elf.adoc#constants
+// [2]: Documentation of TLS data structures
+// https://github.com/riscv-non-isa/riscv-elf-psabi-doc/issues/53
 #define TLS_DTV_OFFSET 0x800
 #endif