diff --git a/crypto/diffie-hellman.c b/crypto/diffie-hellman.c
index 634ef297..0461a430 100644
--- a/crypto/diffie-hellman.c
+++ b/crypto/diffie-hellman.c
@@ -19,12 +19,18 @@ struct dh_extra {
 
 static void dh_group1_construct(dh_ctx *ctx)
 {
+    /* Command to recompute, from the expression in RFC 2412 section E.2:
+spigot -B16 '2^1024 - 2^960 - 1 + 2^64 * ( floor(2^894 pi) + 129093 )'
+     */
     ctx->p = MP_LITERAL(0xFFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF);
     ctx->g = mp_from_integer(2);
 }
 
 static void dh_group14_construct(dh_ctx *ctx)
 {
+    /* Command to recompute, from the expression in RFC 3526 section 3:
+spigot -B16 '2^2048 - 2^1984 - 1 + 2^64 * ( floor(2^1918 pi) + 124476 )'
+     */
     ctx->p = MP_LITERAL(0x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
     ctx->g = mp_from_integer(2);
 }