diff --git a/cache.h b/cache.h
index e0a5f6decd..91e9f7109f 100644
--- a/cache.h
+++ b/cache.h
@@ -359,6 +359,10 @@ int git_config_perm(const char *var, const char *value);
 int adjust_shared_perm(const char *path);
 int safe_create_leading_directories(char *path);
 char *enter_repo(char *path, int strict);
+static inline int is_absolute_path(const char *path)
+{
+	return path[0] == '/' || (isalpha(path[0]) && path[1] == ':');
+}
 
 /* Read and unpack a sha1 file into memory, write memory to a sha1 file */
 extern int sha1_object_info(const unsigned char *, unsigned long *);
diff --git a/trace.c b/trace.c
index 7961a27a2e..344066e88b 100644
--- a/trace.c
+++ b/trace.c
@@ -64,7 +64,7 @@ static int get_trace_fd(int *need_close)
 		return STDERR_FILENO;
 	if (strlen(trace) == 1 && isdigit(*trace))
 		return atoi(trace);
-	if (*trace == '/') {
+	if (is_absolute_path(trace)) {
 		int fd = open(trace, O_WRONLY | O_APPEND | O_CREAT, 0666);
 		if (fd == -1) {
 			fprintf(stderr,