diff --git a/include/jemalloc/internal/prof_inlines_a.h b/include/jemalloc/internal/prof_inlines_a.h
index 471d9853..6716d2f4 100644
--- a/include/jemalloc/internal/prof_inlines_a.h
+++ b/include/jemalloc/internal/prof_inlines_a.h
@@ -71,8 +71,19 @@ prof_accum_cancel(tsdn_t *tsdn, prof_accum_t *prof_accum,
 #endif
 }
 
+JEMALLOC_ALWAYS_INLINE void
+prof_active_assert() {
+	cassert(config_prof);
+	/*
+	 * If opt_prof is off, then prof_active must always be off, regardless
+	 * of whether prof_active_mtx is in effect or not.
+	 */
+	assert(opt_prof || !prof_active);
+}
+
 JEMALLOC_ALWAYS_INLINE bool
 prof_active_get_unlocked(void) {
+	prof_active_assert();
 	/*
 	 * Even if opt_prof is true, sampling can be temporarily disabled by
 	 * setting prof_active to false.  No locking is used when reading
diff --git a/src/ctl.c b/src/ctl.c
index 6bd534a7..fd05c08b 100644
--- a/src/ctl.c
+++ b/src/ctl.c
@@ -2662,7 +2662,8 @@ prof_active_ctl(tsd_t *tsd, const size_t *mib, size_t miblen,
 	bool oldval;
 
 	if (!config_prof) {
-		return ENOENT;
+		ret = ENOENT;
+		goto label_return;
 	}
 
 	if (newp != NULL) {
@@ -2670,7 +2671,12 @@ prof_active_ctl(tsd_t *tsd, const size_t *mib, size_t miblen,
 			ret = EINVAL;
 			goto label_return;
 		}
-		oldval = prof_active_set(tsd_tsdn(tsd), *(bool *)newp);
+		bool val = *(bool *)newp;
+		if (!opt_prof && val) {
+			ret = ENOENT;
+			goto label_return;
+		}
+		oldval = prof_active_set(tsd_tsdn(tsd), val);
 	} else {
 		oldval = prof_active_get(tsd_tsdn(tsd));
 	}
diff --git a/src/prof.c b/src/prof.c
index 9ea4eda4..e00151d3 100644
--- a/src/prof.c
+++ b/src/prof.c
@@ -788,6 +788,7 @@ bool
 prof_active_get(tsdn_t *tsdn) {
 	bool prof_active_current;
 
+	prof_active_assert();
 	malloc_mutex_lock(tsdn, &prof_active_mtx);
 	prof_active_current = prof_active;
 	malloc_mutex_unlock(tsdn, &prof_active_mtx);
@@ -798,10 +799,12 @@ bool
 prof_active_set(tsdn_t *tsdn, bool active) {
 	bool prof_active_old;
 
+	prof_active_assert();
 	malloc_mutex_lock(tsdn, &prof_active_mtx);
 	prof_active_old = prof_active;
 	prof_active = active;
 	malloc_mutex_unlock(tsdn, &prof_active_mtx);
+	prof_active_assert();
 	return prof_active_old;
 }
 
diff --git a/test/unit/mallctl.c b/test/unit/mallctl.c
index 3a75ac04..0e88f314 100644
--- a/test/unit/mallctl.c
+++ b/test/unit/mallctl.c
@@ -762,6 +762,32 @@ TEST_BEGIN(test_arenas_lookup) {
 }
 TEST_END
 
+TEST_BEGIN(test_prof_active) {
+	/*
+	 * If config_prof is off, then the test for prof_active in
+	 * test_mallctl_opt was already enough.
+	 */
+	test_skip_if(!config_prof);
+
+	bool active, old;
+	size_t len = sizeof(bool);
+
+	active = true;
+	assert_d_eq(mallctl("prof.active", NULL, NULL, &active, len), ENOENT,
+	    "Setting prof_active to true should fail when opt_prof is off");
+	old = true;
+	assert_d_eq(mallctl("prof.active", &old, &len, &active, len), ENOENT,
+	    "Setting prof_active to true should fail when opt_prof is off");
+	assert_true(old, "old valud should not be touched when mallctl fails");
+	active = false;
+	assert_d_eq(mallctl("prof.active", NULL, NULL, &active, len), 0,
+	    "Setting prof_active to false should succeed when opt_prof is off");
+	assert_d_eq(mallctl("prof.active", &old, &len, &active, len), 0,
+	    "Setting prof_active to false should succeed when opt_prof is off");
+	assert_false(old, "prof_active should be false when opt_prof is off");
+}
+TEST_END
+
 TEST_BEGIN(test_stats_arenas) {
 #define TEST_STATS_ARENAS(t, name) do {					\
 	t name;								\
@@ -882,6 +908,7 @@ main(void) {
 	    test_arenas_lextent_constants,
 	    test_arenas_create,
 	    test_arenas_lookup,
+	    test_prof_active,
 	    test_stats_arenas,
 	    test_hooks,
 	    test_hooks_exhaustion);