diff --git a/src/spell.c b/src/spell.c
index e5c2f7d..48a2203 100644
--- a/src/spell.c
+++ b/src/spell.c
@@ -253,7 +253,7 @@
 							     MAXWLEN + 1);
     mi.mi_fwordlen = (int)STRLEN(mi.mi_fword);
 
-    if (camel_case)
+    if (camel_case && mi.mi_fwordlen > 0)
 	// Introduce a fake word end space into the folded word.
 	mi.mi_fword[mi.mi_fwordlen - 1] = ' ';