diff --git a/debian/README.source b/debian/README.source
index 7447abac..9a7500a0 100644
--- a/debian/README.source
+++ b/debian/README.source
@@ -22,6 +22,8 @@ and symlinks are managed by the other package llvm-defaults
 
 * For mips, FPXX is enabled.
 
+* For riscv64, the hard-float ABI is used instead of the float one, and
+  the target CPU is set to RV64GC instead of RV64I.
 
 = Libraries =
 
diff --git a/debian/changelog b/debian/changelog
index aaafdc83..cc4b0ff0 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -8,6 +8,7 @@ llvm-toolchain-snapshot (1:10~svn367724-1~exp1) experimental; urgency=medium
     - Always link with -latomic on riscv64.
     - patches/clang-riscv64-multiarch.diff: add multiarch paths for riscv64.
     - patches/clang-riscv64-rv64gc.diff: default to lp64d ABI and rv64gc ISA.
+  * Document riscv64 debian specific changes in README.source.
 
   [ Sylvestre Ledru ]
   * New snapshot release