diff --git a/tests/scripts/depends-hashes.pl b/tests/scripts/depends-hashes.pl
index 96cc902..46628a7 100755
--- a/tests/scripts/depends-hashes.pl
+++ b/tests/scripts/depends-hashes.pl
@@ -37,6 +37,7 @@
 my $ssl_sed_cmd = 's/^#define \(MBEDTLS_SSL.*\)/\1/p';
 my @ssl = split( /\s+/, `sed -n -e '$ssl_sed_cmd' $config_h` );
 
+# for md we want to catch MD5_C but not MD_C, hence the extra dot
 my $mdx_sed_cmd = 's/^#define \(MBEDTLS_MD..*_C\)/\1/p';
 my $sha_sed_cmd = 's/^#define \(MBEDTLS_SHA.*_C\)/\1/p';
 my @hashes = split( /\s+/,