diff --git a/src/spellsuggest.c b/src/spellsuggest.c
index 5b460a3..8f97565 100644
--- a/src/spellsuggest.c
+++ b/src/spellsuggest.c
@@ -1973,7 +1973,8 @@
 			    sp->ts_isdiff = (newscore != 0)
 						       ? DIFF_YES : DIFF_NONE;
 			}
-			else if (sp->ts_isdiff == DIFF_INSERT)
+			else if (sp->ts_isdiff == DIFF_INSERT
+							    && sp->ts_fidx > 0)
 			    // When inserting trail bytes don't advance in the
 			    // bad word.
 			    --sp->ts_fidx;