diff --git a/Makefile b/Makefile
index 9016fba9..ee32259d 100644
--- a/Makefile
+++ b/Makefile
@@ -67,7 +67,7 @@ install: $(LIBRARIES) $(TOOLS) $(HEADERS)
 		&& cp -t $(SANDBOX)$(mandir)/man1 $(MANPAGES)
 
 clean:
-	rm -rf $(TOOLS )$(TESTS) @* *.[ao] *.[ls]o *~ testdb/* *.gcov
+	rm -rf $(TOOLS) $(TESTS) @* *.[ao] *.[ls]o *~ testdb/* *.gcov
 
 tests:	$(TESTS)
 
@@ -199,8 +199,9 @@ bench: bench-lmdb.txt bench-mdbx.txt
 endif
 
 ci-rule = ( CC=$$(which $1); if [ -n "$$CC" ]; then \
-		CC=$$(readlink -f $$CC); echo -n "probe by $2 ($$CC): " && \
-		$(MAKE) XCFLAGS="-UNDEBUG -DMDB_DEBUG=2" clean >$1.log 2>$1.err && $(MAKE) all check 1>$1.log 2>$1.err && echo "OK" \
+		echo -n "probe by $2 ($$CC): " && \
+		$(MAKE) clean >$1.log 2>$1.err && \
+		$(MAKE) CC=$$(readlink -f $$CC) XCFLAGS="-UNDEBUG -DMDB_DEBUG=2" all check 1>$1.log 2>$1.err && echo "OK" \
 			|| ( echo "FAILED"; cat $1.err >&2; exit 1 ); \
 	else echo "no $2 ($1) for probe"; fi; )
 ci:
diff --git a/mdb.c b/mdb.c
index 4caa8c5f..3612bdad 100644
--- a/mdb.c
+++ b/mdb.c
@@ -1223,7 +1223,7 @@ static txnid_t mdbx_oomkick(MDB_env *env, txnid_t oldest);
 #endif /* MDBX_MODE_ENABLED */
 
 static void mdb_debug_log(int type, const char *function, int line, const char *fmt, ...)
-	__attribute__((format(gnu_printf, 4, 5)));
+	__attribute__((format(printf, 4, 5)));
 
 #if MDB_DEBUG
 	static txnid_t mdb_debug_edge;
@@ -1403,7 +1403,7 @@ mdb_page_list(MDB_page *mp)
 			pgno, ((MDB_meta *)PAGEDATA(mp))->mm_txnid);
 		return;
 	default:
-		mdb_print("Bad page %zu flags 0x%u\n", pgno, mp->mp_flags);
+		mdb_print("Bad page %zu flags 0x%X\n", pgno, mp->mp_flags);
 		return;
 	}
 
@@ -7303,6 +7303,7 @@ mdb_node_add(MDB_cursor *mc, indx_t indx,
 		key ? key->mv_size : 0, key ? DKEY(key) : "null");
 
 	if (IS_LEAF2(mp)) {
+		mdb_cassert(mc, key);
 		/* Move higher keys up one slot. */
 		int ksize = mc->mc_db->md_xsize, dif;
 		char *ptr = LEAF2KEY(mp, indx, ksize);