diff --git a/luna/src/Check.cpp b/luna/src/Check.cpp
index b57856e7..5d706837 100644
--- a/luna/src/Check.cpp
+++ b/luna/src/Check.cpp
@@ -1,6 +1,11 @@
 #include <luna/Attributes.h>
 
-_weak [[noreturn]] bool __check_failed(const char*, const char*, const char*, const char*)
+#include <stdio.h>
+#include <stdlib.h>
+
+_weak [[noreturn]] bool __check_failed(const char* file, const char* line, const char* func, const char* expr)
 {
-    __builtin_trap();
+    // FIXME: Output to standard error instead of standard output.
+    printf("Check failed at %s:%s in %s: %s\n", file, line, func, expr);
+    abort();
 }