diff --git a/libuavcan_drivers/lpc11c24/driver/src/clock.cpp b/libuavcan_drivers/lpc11c24/driver/src/clock.cpp
index 07098d6c5e..a9d299f063 100644
--- a/libuavcan_drivers/lpc11c24/driver/src/clock.cpp
+++ b/libuavcan_drivers/lpc11c24/driver/src/clock.cpp
@@ -82,6 +82,10 @@ std::uint64_t getUtcUSecFromCanInterrupt()
 
 uavcan::MonotonicTime getMonotonic()
 {
+    if (!initialized)
+    {
+        fail();
+    }
     std::uint64_t usec = 0;
     {
         CriticalSectionLocker locker;
@@ -92,6 +96,10 @@ uavcan::MonotonicTime getMonotonic()
 
 uavcan::UtcTime getUtc()
 {
+    if (!initialized)
+    {
+        fail();
+    }
     std::uint64_t usec = 0;
     if (utc_set)
     {