diff --git a/lib/convert.c b/lib/convert.c
index 036506842c..74d452b0de 100644
--- a/lib/convert.c
+++ b/lib/convert.c
@@ -102,7 +102,7 @@ static int convert_is_binary(const struct text_stat *stats)
 	return 0;
 }
 
-static unsigned int gather_convert_stats(const char *data, unsigned long size)
+static unsigned int gather_convert_stats(const char *data, size_t size)
 {
 	struct text_stat stats;
 	int ret = 0;
@@ -119,7 +119,7 @@ static unsigned int gather_convert_stats(const char *data, unsigned long size)
 	return ret;
 }
 
-static const char *gather_convert_stats_ascii(const char *data, unsigned long size)
+static const char *gather_convert_stats_ascii(const char *data, size_t size)
 {
 	unsigned int convert_stats = gather_convert_stats(data, size);