Thanks TripleHound, interesting reading, but it wasn't any of those threads. From what I can determine "est_count" appears in several test files in the trunk but doesn't feature in the amalgamation. tom@sp4:~/sqlite$ grep -Rl 'est_count' . ./ext/fts5/test/fts5aa.test ./src/test_func.c ./test/fuzz_malloc.test ./test/memleak.test ./test/walcrash3.test ./test/tester.tcl ./test/soak.test ./test/backcompat.test EDIT: Ignore the above list. I didn't include the grep -w option so it was showing up files containing "test_counter". It returned nothing with -w set.