Use srand_deterministic(3) if available.
Index: src/html.c
--- src/html.c.orig
+++ src/html.c
@@ -834,7 +834,7 @@ void mmd_export_token_html(DString * out, const char *
 					temp_short = scratch->footnote_being_printed;
 
 					if (scratch->extensions & EXT_RANDOM_FOOT) {
-						srand(scratch->random_seed_base + temp_short);
+						srand_deterministic(scratch->random_seed_base + temp_short);
 						temp_short = rand() % 32000 + 1;
 					}
 
@@ -1611,7 +1611,7 @@ parse_citation:
 					// This is a re-use of a previously used note
 
 					if (scratch->extensions & EXT_RANDOM_FOOT) {
-						srand(scratch->random_seed_base + temp_short);
+						srand_deterministic(scratch->random_seed_base + temp_short);
 						temp_short3 = rand() % 32000 + 1;
 					} else {
 						temp_short3 = temp_short;
@@ -1623,7 +1623,7 @@ parse_citation:
 					// This is the first time this note was used
 
 					if (scratch->extensions & EXT_RANDOM_FOOT) {
-						srand(scratch->random_seed_base + temp_short);
+						srand_deterministic(scratch->random_seed_base + temp_short);
 						temp_short3 = rand() % 32000 + 1;
 					} else {
 						temp_short3 = temp_short;