diff --color -Naur tex4ht-1.0.2009_06_11_1038/src/tex4ht.c tex4ht-1.0.2009_06_11_1038_patched/src/tex4ht.c
--- tex4ht-1.0.2009_06_11_1038/src/tex4ht.c	2009-01-31 13:40:37.000000000 +0100
+++ tex4ht-1.0.2009_06_11_1038_patched/src/tex4ht.c	2023-10-14 22:36:19.549394479 +0200
@@ -7039,7 +7039,7 @@
 
 max_htf_4hf_n = 256;
 htf_4hf = m_alloc(struct htf_4hf_rec, 256);
-
+memset (htf_4hf, 0, 256 * sizeof (struct htf_4hf_rec));
 
       
 err = FALSE;
@@ -8738,7 +8738,7 @@
 
    
 if( span_on && !in_span_ch  && !ignore_chs && !in_accenting
-            && (default_font != font_tbl[cur_fnt].num) ){
+            && cur_fnt >= 0 && (default_font != font_tbl[cur_fnt].num) ){
   if(  (ch < 137) && (ch != 
 132 
 ) ){