diff --git a/configure.ac b/configure.ac
index bd59fabd7..10ae2c2eb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -120,6 +120,7 @@ CC_CHECK_FLAGS_APPEND([AM_CFLAGS],[CFLAGS],[ \
   -Wdate-time \
   -Wnested-externs \
   -Wconversion \
+  -Wno-format-nonliteral \
   -Werror \
 ])
 # To enable:
diff --git a/src/lib/sm.c b/src/lib/sm.c
index 5c1e696fd..9453c1fca 100644
--- a/src/lib/sm.c
+++ b/src/lib/sm.c
@@ -22,16 +22,27 @@ int sm_state(const struct sm *m)
 
 static inline void sm_obs(const struct sm *m)
 {
-	tracef("%s pid: %d sm_id: %" PRIu64 " %s |\n",
+	tracef("%s pid: %d sm_id: %" PRIu64 " %s |",
 		m->name, m->pid, m->id, m->conf[sm_state(m)].name);
 }
 
 void sm_relate(const struct sm *from, const struct sm *to)
 {
-	tracef("%s-to-%s opid: %d dpid: %d id: %" PRIu64 " id: %" PRIu64 " |\n",
+	tracef("%s-to-%s opid: %d dpid: %d id: %" PRIu64 " id: %" PRIu64 " |",
 		from->name, to->name, from->pid, to->pid, from->id, to->id);
 }
 
+void sm_attr(const struct sm *m, const char *k, const char *fmt, ...)
+{
+	char v[SM_MAX_ATTR_LENGTH];
+	va_list ap;
+	va_start(ap, fmt);
+	vsnprintf(v, sizeof(v), fmt, ap);
+	va_end(ap);
+	tracef("%s-attr pid: %d sm_id: %" PRIu64 " %s %s |",
+	       m->name, m->pid, m->id, k, v);
+}
+
 void sm_init(struct sm *m,
 	     bool (*invariant)(const struct sm *, int),
 	     bool (*is_locked)(const struct sm *),
@@ -49,6 +60,7 @@ void sm_init(struct sm *m,
 	m->is_locked = is_locked;
 	m->id = ++id;
 	m->pid = getpid();
+	m->rc = 0;
 	snprintf(m->name, SM_MAX_NAME_LENGTH, "%s", name);
 	sm_obs(m);
 
@@ -82,12 +94,13 @@ void sm_fail(struct sm *m, int fail_state, int rc)
 
 	m->rc = rc;
 	m->state = fail_state;
+	sm_obs(m);
 	POST(m->invariant != NULL && m->invariant(m, prev));
 }
 
 static __attribute__((noinline)) bool check_failed(const char *f, int n, const char *s)
 {
-	tracef("%s:%d check failed: %s\n", f, n, s);
+	tracef("%s:%d check failed: %s", f, n, s);
 	return false;
 }
 
diff --git a/src/lib/sm.h b/src/lib/sm.h
index e4c9b2a39..d7f72c23f 100644
--- a/src/lib/sm.h
+++ b/src/lib/sm.h
@@ -10,6 +10,7 @@
 #define CHECK(cond) sm_check((cond), __FILE__, __LINE__, #cond)
 
 #define SM_MAX_NAME_LENGTH 50
+#define SM_MAX_ATTR_LENGTH 100
 
 enum {
 	SM_PREV_NONE = -1,
@@ -54,5 +55,9 @@ int sm_state(const struct sm *m);
 bool sm_check(bool b, const char *f, int n, const char *s);
 /* Relates one state machine to another for observability. */
 void sm_relate(const struct sm *from, const struct sm *to);
+/**
+ * Records an attribute of a state machine for observability.
+ */
+void sm_attr(const struct sm *m, const char *k, const char *fmt, ...);
 
 #endif /* __LIB_SM__ */
diff --git a/src/logger.c b/src/logger.c
index 92bdf919e..78614249d 100644
--- a/src/logger.c
+++ b/src/logger.c
@@ -36,10 +36,7 @@ void loggerDefaultEmit(void *data, int level, const char *fmt, va_list args)
 
 	/* Then render the message, possibly truncating it. */
 	n = EMIT_BUF_LEN - strlen(buf) - 1;
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wformat-nonliteral"
 	vsnprintf(cursor, n, fmt, args);
-#pragma GCC diagnostic pop
 
 	fprintf(stderr, "%s\n", buf);
 }
diff --git a/test/lib/logger.c b/test/lib/logger.c
index 2970254fa..20d2588c4 100644
--- a/test/lib/logger.c
+++ b/test/lib/logger.c
@@ -34,10 +34,7 @@ void test_logger_emit(void *data, int level, const char *format, va_list args)
 
 	sprintf(buf + strlen(buf), "%2d -> [%s] ", t->id, level_name);
 
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wformat-nonliteral"
 	vsnprintf(buf + strlen(buf), 1024 - strlen(buf), format, args);
-#pragma GCC diagnostic pop
 	munit_log(MUNIT_LOG_INFO, buf);
 	return;