diff --git a/link-grammar/disjunct-utils.h b/link-grammar/disjunct-utils.h
index 9dceb149c..e1fd74333 100644
--- a/link-grammar/disjunct-utils.h
+++ b/link-grammar/disjunct-utils.h
@@ -22,7 +22,7 @@
 #include "parse/histogram.h"            // count_t
 
 // Can undefine VERIFY_MATCH_LIST when done debugging...
-#define VERIFY_MATCH_LIST
+// #define VERIFY_MATCH_LIST
 
 /* On a 64-bit machine, this struct should be exactly (6+2)*8=64 bytes long.
  * Lets try to keep it that way (for performance). */
diff --git a/link-grammar/parse/count.c b/link-grammar/parse/count.c
index 1c636f672..3233cbe2a 100644
--- a/link-grammar/parse/count.c
+++ b/link-grammar/parse/count.c
@@ -779,8 +779,10 @@ static void lrcnt_cache_match_list(wordvecp lrcnt_cache, count_context_t *ctxt,
 	}
 	dassert(dcnt > 0, "No disjuncts to cache");
 	//if (dcnt == i-mlb) return NULL;
+#ifdef VERIFY_MATCH_LIST
 	lgdebug(+9, "MATCH_LIST %9d dir=%d mlb %zu cached %zu/%zu\n",
 	        get_match_list_element(mchxt, mlb)->match_id, dir, mlb, dcnt, i-mlb);
+#endif
 
 	match_list_cache *ml = pool_alloc_vec(ctxt->mlc_pool, dcnt + 1);
 	if (ml == NULL) return; /* Cannot allocate cache array */
diff --git a/link-grammar/parse/fast-match.c b/link-grammar/parse/fast-match.c
index a6e9d0e7f..e41cf32e0 100644
--- a/link-grammar/parse/fast-match.c
+++ b/link-grammar/parse/fast-match.c
@@ -595,14 +595,14 @@ form_match_list(fast_matcher_t *ctxt, int w,
 	}
 
 #ifdef VERIFY_MATCH_LIST
-	static uint16_t id = 0;
-	uint16_t lid = ++id; /* A stable local copy, for multi-threading support. */
+	static _Atomic(uint16_t) id = 0;
+	const uint16_t lid = ++id; /* A stable local copy, for multi-threading support. */
 #else
 	const uint16_t lid = 0;
 #endif
 
 	lgdebug(+D_FAST_MATCHER, "MATCH_LIST %c%c %5d mlb %zu\n",
-	        (mlcl == NULL) ? ' ' : 'L', (mlcr == NULL) ? ' ' : 'R', id, front);
+	        (mlcl == NULL) ? ' ' : 'L', (mlcr == NULL) ? ' ' : 'R', lid, front);
 
 	if (mlcr == NULL)
 	{
diff --git a/link-grammar/parse/fast-match.h b/link-grammar/parse/fast-match.h
index 37618b5d8..01c6cfaa1 100644
--- a/link-grammar/parse/fast-match.h
+++ b/link-grammar/parse/fast-match.h
@@ -71,12 +71,14 @@ static inline Disjunct *get_match_list_element(fast_matcher_t *ctxt, size_t mli)
 static inline void pop_match_list(fast_matcher_t *ctxt, size_t match_list_last)
 {
 	ctxt->match_list_end = match_list_last;
+#ifdef VERIFY_MATCH_LIST
 	if (verbosity_level(9))
 	{
 		if (get_match_list_element(ctxt, match_list_last) != NULL)
 			lgdebug(+9, "MATCH_LIST %9d pop\n",
 			        get_match_list_element(ctxt, match_list_last)->match_id);
 	}
+#endif
 }
 
 /**