diff --git a/src/common/mmap.c b/src/common/mmap.c
index 45bdf7a5d3b..8e6dc012622 100644
--- a/src/common/mmap.c
+++ b/src/common/mmap.c
@@ -355,7 +355,13 @@ util_range_register(const void *addr, size_t len, const char *path,
 	LOG(3, "addr %p len %zu path %s type %d", addr, len, path, type);
 
 	/* check if not tracked already */
-	ASSERTeq(util_range_find((uintptr_t)addr, len), NULL);
+	if (util_range_find((uintptr_t)addr, len) != NULL) {
+		ERR(
+		"duplicated persistent memory range; presumably unmapped with munmap() instead of pmem_unmap(): addr %p len %zu",
+			addr, len);
+		errno = ENOMEM;
+		return -1;
+	}
 
 	struct map_tracker *mt;
 	mt  = Malloc(sizeof(struct map_tracker));
diff --git a/src/test/pmem_is_pmem_posix/TEST4 b/src/test/pmem_is_pmem_posix/TEST4
index e33c733a88b..774242ba985 100755
--- a/src/test/pmem_is_pmem_posix/TEST4
+++ b/src/test/pmem_is_pmem_posix/TEST4
@@ -74,7 +74,11 @@ expect_normal_exit ./pmem_is_pmem_posix$EXESUFFIX\
 	t 0x000000020000 0x10000\
 	t 0x000000030000 0x10000\
 	t 0x000000040000 0x10000\
-	t 0x000000010000 0x40000
+	t 0x000000010000 0x40000\
+	a 0x000000030000 0x20000 DEV_DAX\
+	a 0x000000020000 0x20000 DEV_DAX\
+	t 0x000000030000 0x20000\
+	t 0x000000020000 0x20000
 
 check
 
diff --git a/src/test/pmem_is_pmem_posix/out4.log.match b/src/test/pmem_is_pmem_posix/out4.log.match
index 1f128d19475..2045fc5cb52 100644
--- a/src/test/pmem_is_pmem_posix/out4.log.match
+++ b/src/test/pmem_is_pmem_posix/out4.log.match
@@ -25,4 +25,7 @@ addr 0x20000 len 65536 is_pmem 0
 addr 0x30000 len 65536 is_pmem 0
 addr 0x40000 len 65536 is_pmem 0
 addr 0x10000 len 262144 is_pmem 0
+duplicated persistent memory range; presumably unmapped with munmap() instead of pmem_unmap(): addr 0x20000 len 131072
+addr 0x30000 len 131072 is_pmem 1
+addr 0x20000 len 131072 is_pmem 0
 pmem_is_pmem_posix/TEST4: DONE
diff --git a/src/test/pmem_is_pmem_posix/pmem_is_pmem_posix.c b/src/test/pmem_is_pmem_posix/pmem_is_pmem_posix.c
index 1a5c60dd56a..8596fbe5825 100644
--- a/src/test/pmem_is_pmem_posix/pmem_is_pmem_posix.c
+++ b/src/test/pmem_is_pmem_posix/pmem_is_pmem_posix.c
@@ -81,7 +81,8 @@ main(int argc, char *argv[])
 		case 'a':
 			ret = util_range_register(addr, len, "",
 					str2type(argv[i + 3]));
-			UT_ASSERTeq(ret, 0);
+			if (ret != 0)
+				UT_OUT("%s", pmem_errormsg());
 			i += 4;
 			break;
 		case 'r':