diff --git a/src/basic/fd-util.c b/src/basic/fd-util.c
index f3863722ee..a0820a9667 100644
--- a/src/basic/fd-util.c
+++ b/src/basic/fd-util.c
@@ -368,7 +368,7 @@ bool fdname_is_valid(const char *s) {
 }
 
 int fd_get_path(int fd, char **ret) {
-        char procfs_path[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(int)];
+        char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int)];
         int r;
 
         xsprintf(procfs_path, "/proc/self/fd/%i", fd);
diff --git a/src/basic/macro.h b/src/basic/macro.h
index 78679083e8..02d22de833 100644
--- a/src/basic/macro.h
+++ b/src/basic/macro.h
@@ -144,6 +144,14 @@ static inline unsigned long ALIGN_POWER2(unsigned long u) {
                 !__builtin_types_compatible_p(typeof(x), typeof(&*(x))), \
                 sizeof(x)/sizeof((x)[0]),                                \
                 (void)0))
+
+/*
+ * STRLEN - return the length of a string literal, minus the trailing NUL byte.
+ *          Contrary to strlen(), this is a constant expression.
+ * @x: a string literal.
+ */
+#define STRLEN(x) (sizeof(""x"") - 1)
+
 /*
  * container_of - cast a member of a structure out to the containing structure
  * @ptr: the pointer to the member.
diff --git a/src/libsystemd-network/sd-dhcp-lease.c b/src/libsystemd-network/sd-dhcp-lease.c
index 7063bd986e..a186bca38f 100644
--- a/src/libsystemd-network/sd-dhcp-lease.c
+++ b/src/libsystemd-network/sd-dhcp-lease.c
@@ -987,7 +987,7 @@ int dhcp_lease_save(sd_dhcp_lease *lease, const char *lease_file) {
         }
 
         LIST_FOREACH(options, option, lease->private_options) {
-                char key[strlen("OPTION_000")+1];
+                char key[STRLEN("OPTION_000")+1];
 
                 xsprintf(key, "OPTION_%" PRIu8, option->tag);
                 r = serialize_dhcp_option(f, key, option->data, option->length);