diff --git a/src/Makefile b/src/Makefile
index b23af1d..b9fd929 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -1,6 +1,6 @@
 OBJS=main.o sysinput.o fbinit.o fbprimitive.o log.o gpio.o msg_queue.o time_func.o config.o splash.o
 LIBS=-lbcm2835 -lpthread
-CFLAGS=-g
+CFLAGS=-g -O -DDEBUG_ASSERT
 
 upiwin: $(OBJS)
 	gcc -o upiwin $(OBJS) $(LIBS)
diff --git a/src/config.c b/src/config.c
index 4b6dd20..e940919 100644
--- a/src/config.c
+++ b/src/config.c
@@ -47,8 +47,10 @@ static void run_exit_funcs(void)
     p = exitfuncs;
     exitfuncs = p->next;
     for (i = p->num_funcs - 1; i >= 0; i--)
-      if (p->funcs[i])
-        (*(p->funcs[i]))();
+    {
+      ASSERT(p->funcs[i]);
+      (*(p->funcs[i]))();
+    }
     free(p);
   }
 }
diff --git a/src/log.c b/src/log.c
index de98b14..81afc30 100644
--- a/src/log.c
+++ b/src/log.c
@@ -23,3 +23,8 @@ void Log(int level, const char *format, ...)
   strftime(timestamp, 32, "%F %T", &tm);
   printf("%s.%06u %s %s\n", timestamp, tv.tv_usec, severities[level], buf);
 }
+
+void Log_assert_failed(const char *test, const char *file, int line)
+{
+  Log(LERROR, "ASSERT FAILED: %s at %s:%d", test, file, line);
+}
diff --git a/src/log.h b/src/log.h
index 8c040b8..82145f5 100644
--- a/src/log.h
+++ b/src/log.h
@@ -8,5 +8,17 @@
 #define LDEBUG 4
 
 extern void Log(int level, const char *format, ...);
+extern void Log_assert_failed(const char *test, const char *file, int line);
+
+#define THIS_FILE __FILE__
+#define DECLARE_THIS_FILE() static const char THIS_FILE[] = __FILE__
+
+#ifdef DEBUG_ASSERT
+#define ASSERT(x)  ((x) ? (void)0 : Log_assert_failed(#x, THIS_FILE, __LINE__))
+#define VERIFY(x)  ASSERT(x)
+#else
+#define ASSERT(x)  ((void)0)
+#define VERIFY(x)  ((void)(x))
+#endif
 
 #endif /* __LOG_H_INCLUDED */