diff --git a/src/fuzz/fuzz-calendarspec.c b/src/fuzz/fuzz-calendarspec.c
index ea027b8f66e7b..573a48a48b47e 100644
--- a/src/fuzz/fuzz-calendarspec.c
+++ b/src/fuzz/fuzz-calendarspec.c
@@ -15,7 +15,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         if (!getenv("SYSTEMD_LOG_LEVEL"))
                 log_set_max_level(LOG_CRIT);
 
-        str = memdup_suffix0(data, size);
+        assert_se(str = memdup_suffix0(data, size));
 
         size_t l1 = strlen(str);
         const char* usecs = l1 < size ? str + l1 + 1 : "";
diff --git a/src/fuzz/fuzz-time-util.c b/src/fuzz/fuzz-time-util.c
index f1c95ae09b830..8e6cb8553b8d2 100644
--- a/src/fuzz/fuzz-time-util.c
+++ b/src/fuzz/fuzz-time-util.c
@@ -12,7 +12,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         if (!getenv("SYSTEMD_LOG_LEVEL"))
                 log_set_max_level(LOG_CRIT);
 
-        str = memdup_suffix0(data, size);
+        assert_se(str = memdup_suffix0(data, size));
 
         (void) parse_timestamp(str, &usec);
         (void) parse_sec(str, &usec);