diff -r 952c2df7e7ac -r 477404eb380e src/string.c
--- a/src/string.c	Sun Dec 29 11:29:17 2019 +0100
+++ b/src/string.c	Sun Dec 29 11:30:39 2019 +0100
@@ -776,6 +776,9 @@
     } while (curbuf);
     memcpy(destptr, str.ptr+srcidx, str.length-srcidx);
 
+    /* Free index buffer */
+    scstrrepl_free_ibuf(firstbuf);
+
     return result;
 }