diff --git a/CRT.c b/CRT.c
index 30236a3b..3a665496 100644
--- a/CRT.c
+++ b/CRT.c
@@ -13,6 +13,7 @@ in the source distribution for its full text.
 #include <fcntl.h>
 #include <langinfo.h>
 #include <signal.h>
+#include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -844,6 +845,16 @@ static void dumpStderr(void) {
    stderrRedirectNewFd = -1;
 }
 
+void CRT_debug_impl(const char* file, size_t lineno, const char* func, const char* fmt, ...)  {
+   va_list args;
+
+   fprintf(stderr, "[%s:%zu (%s)]: ", file, lineno, func);
+   va_start(args, fmt);
+   vfprintf(stderr, fmt, args);
+   va_end(args);
+   fprintf(stderr, "\n");
+}
+
 #else /* !NDEBUG */
 
 static void redirectStderr(void) {
diff --git a/CRT.h b/CRT.h
index 0b6302fc..eae4722d 100644
--- a/CRT.h
+++ b/CRT.h
@@ -150,6 +150,13 @@ typedef enum ColorElements_ {
 
 void CRT_fatalError(const char* note) ATTR_NORETURN;
 
+#ifdef NDEBUG
+# define CRT_debug(...)
+#else
+void CRT_debug_impl(const char* file, size_t lineno, const char* func, const char* fmt, ...) ATTR_FORMAT(printf, 4, 5);
+# define CRT_debug(...) CRT_debug_impl(__FILE__, __LINE__, __func__, __VA_ARGS__)
+#endif
+
 void CRT_handleSIGSEGV(int signal) ATTR_NORETURN;
 
 #define KEY_WHEELUP   KEY_F(30)