diff --git a/programs/benchmark.c b/programs/benchmark.c
index cb852a7..d0629bb 100644
--- a/programs/benchmark.c
+++ b/programs/benchmark.c
@@ -503,7 +503,7 @@ tmain(int argc, tchar *argv[])
 	int i;
 	int ret;
 
-	program_invocation_name = get_filename(argv[0]);
+	begin_program(argv);
 
 	while ((opt_char = tgetopt(argc, argv, optstring)) != -1) {
 		switch (opt_char) {
diff --git a/programs/checksum.c b/programs/checksum.c
index bd3c40d..6c0133d 100644
--- a/programs/checksum.c
+++ b/programs/checksum.c
@@ -115,7 +115,7 @@ tmain(int argc, tchar *argv[])
 	int i;
 	int ret;
 
-	program_invocation_name = get_filename(argv[0]);
+	begin_program(argv);
 
 	while ((opt_char = tgetopt(argc, argv, optstring)) != -1) {
 		switch (opt_char) {
diff --git a/programs/gzip.c b/programs/gzip.c
index 258babc..546f969 100644
--- a/programs/gzip.c
+++ b/programs/gzip.c
@@ -528,7 +528,7 @@ tmain(int argc, tchar *argv[])
 	int i;
 	int ret;
 
-	program_invocation_name = get_filename(argv[0]);
+	begin_program(argv);
 
 	options.to_stdout = false;
 	options.decompress = is_gunzip();
diff --git a/programs/prog_util.c b/programs/prog_util.c
index 7cc3bc6..06d3d46 100644
--- a/programs/prog_util.c
+++ b/programs/prog_util.c
@@ -112,7 +112,7 @@ xmalloc(size_t size)
  * properly for directories, since a path to a directory might have trailing
  * slashes.
  */
-const tchar *
+static const tchar *
 get_filename(const tchar *path)
 {
 	const tchar *slash = tstrrchr(path, '/');
@@ -126,6 +126,12 @@ get_filename(const tchar *path)
 	return path;
 }
 
+void
+begin_program(tchar *argv[])
+{
+	program_invocation_name = get_filename(argv[0]);
+}
+
 /* Create a copy of 'path' surrounded by double quotes */
 static tchar *
 quote_path(const tchar *path)
diff --git a/programs/prog_util.h b/programs/prog_util.h
index 7bacf1a..71f7160 100644
--- a/programs/prog_util.h
+++ b/programs/prog_util.h
@@ -119,7 +119,7 @@ void _printf(1, 2) msg_errno(const char *fmt, ...);
 
 void *xmalloc(size_t size);
 
-const tchar *get_filename(const tchar *path);
+void begin_program(tchar *argv[]);
 
 struct file_stream {
 	int fd;
diff --git a/programs/test_checksums.c b/programs/test_checksums.c
index 686fafb..99fad7d 100644
--- a/programs/test_checksums.c
+++ b/programs/test_checksums.c
@@ -151,7 +151,7 @@ tmain(int argc, tchar *argv[])
 	u8 *buffer = xmalloc(32768);
 	u8 *guarded_buf_start, *guarded_buf_end;
 
-	program_invocation_name = get_filename(argv[0]);
+	begin_program(argv);
 
 	alloc_guarded_buffer(32768, &guarded_buf_start, &guarded_buf_end);
 
diff --git a/programs/test_incomplete_codes.c b/programs/test_incomplete_codes.c
index 436cd9b..4e441bc 100644
--- a/programs/test_incomplete_codes.c
+++ b/programs/test_incomplete_codes.c
@@ -374,7 +374,7 @@ test_singleton_offset_code_notsymzero(void)
 int
 tmain(int argc, tchar *argv[])
 {
-	program_invocation_name = get_filename(argv[0]);
+	begin_program(argv);
 
 	test_empty_offset_code();
 	test_singleton_litrunlen_code();
diff --git a/programs/test_slow_decompression.c b/programs/test_slow_decompression.c
index f691960..d5ac262 100644
--- a/programs/test_slow_decompression.c
+++ b/programs/test_slow_decompression.c
@@ -430,7 +430,7 @@ tmain(int argc, tchar *argv[])
 	u8 out[10000];
 	u64 t, tz;
 
-	program_invocation_name = get_filename(argv[0]);
+	begin_program(argv);
 
 	begin_performance_test();
 
diff --git a/programs/test_trailing_bytes.c b/programs/test_trailing_bytes.c
index ca23378..bf33793 100644
--- a/programs/test_trailing_bytes.c
+++ b/programs/test_trailing_bytes.c
@@ -65,7 +65,7 @@ tmain(int argc, tchar *argv[])
 	size_t actual_compressed_nbytes;
 	size_t actual_decompressed_nbytes;
 
-	program_invocation_name = get_filename(argv[0]);
+	begin_program(argv);
 
 	ASSERT(compressed_nbytes_avail < compressed_nbytes_total);