diff --git a/src/trace.c b/src/trace.c
index 1aa89323..e4a45cf5 100644
--- a/src/trace.c
+++ b/src/trace.c
@@ -16,9 +16,7 @@
 #include <time.h>
 #include <unistd.h>
 
-#if !defined(_countof)
-#define _countof(a) ((int)(sizeof((a)) / sizeof(*(a))))
-#endif
+#define tf_countof(a) ((int)(sizeof((a)) / sizeof(*(a))))
 
 enum
 {
@@ -139,7 +137,7 @@ void tf_trace_counter(tf_trace_t* trace, const char* name, int argc, const char*
 	{
 		p += snprintf(line + p, sizeof(line) - p, "\"%s\": %" PRId64 "%s", arg_names[i], arg_values[i], i == argc - 1 ? "}}," : ", ");
 	}
-	p = tf_min(p, _countof(line));
+	p = tf_min(p, tf_countof(line));
 	trace->callback(trace, line, p, trace->user_data);
 }
 
@@ -229,7 +227,7 @@ static tf_trace_thread_t* _tf_trace_get_thread(tf_trace_t* trace, pthread_t self
 static void _tf_push_stack(tf_trace_t* trace, pthread_t self, const char* name, void* tag)
 {
 	tf_trace_thread_t* thread = _tf_trace_get_thread(trace, self);
-	if (!thread->stack || thread->stack->count + 1 > (int)_countof(thread->stack->names))
+	if (!thread->stack || thread->stack->count + 1 > tf_countof(thread->stack->names))
 	{
 		tf_trace_stack_t* stack = tf_malloc(sizeof(tf_trace_stack_t));
 		memset(stack, 0, sizeof(*stack));
@@ -237,7 +235,7 @@ static void _tf_push_stack(tf_trace_t* trace, pthread_t self, const char* name,
 		thread->stack = stack;
 	}
 	tf_trace_stack_t* stack = thread->stack;
-	while (stack->count == 0 && stack->next && stack->next->count + 1 <= (int)_countof(thread->stack->names))
+	while (stack->count == 0 && stack->next && stack->next->count + 1 <= tf_countof(thread->stack->names))
 	{
 		stack = stack->next;
 	}
@@ -280,7 +278,7 @@ static void _tf_trace_begin_tagged(tf_trace_t* trace, const char* name, void* ta
 	int p = snprintf(line, sizeof(line), "{\"ph\": \"B\", \"pid\": %d, \"tid\": \"0x%" PRIx64 "\", \"ts\": %" PRId64 ", \"name\": \"", getpid(), (int64_t)self, _trace_ts());
 	p += _tf_trace_escape_name(line + p, sizeof(line) - p, name);
 	p += snprintf(line + p, sizeof(line) - p, "\"},");
-	p = tf_min(p, _countof(line));
+	p = tf_min(p, tf_countof(line));
 	trace->callback(trace, line, p, trace->user_data);
 }
 
@@ -307,7 +305,7 @@ static void _tf_trace_end_tagged(tf_trace_t* trace, void* tag)
 	int p = snprintf(line, sizeof(line), "{\"ph\": \"E\", \"pid\": %d, \"tid\": \"0x%" PRIx64 "\", \"ts\": %" PRId64 ", \"name\": \"", getpid(), (int64_t)pthread_self(), _trace_ts());
 	p += _tf_trace_escape_name(line + p, sizeof(line) - p, name);
 	p += snprintf(line + p, sizeof(line) - p,  "\"},");
-	p = tf_min(p, _countof(line));
+	p = tf_min(p, tf_countof(line));
 	trace->callback(trace, line, p, trace->user_data);
 }