diff --git a/Build.PL b/Build.PL
index 65bea3222..bf0e5bf53 100644
--- a/Build.PL
+++ b/Build.PL
@@ -19,6 +19,7 @@ my %prereqs = qw(
     Moo                             1.003001
     Scalar::Util                    0
     Storable                        0
+    Test::Harness                   0
     Test::More                      0
     IO::Scalar                      0
     Time::HiRes                     0
@@ -40,12 +41,12 @@ if ($gui) {
     );
 }
 
-my $missing_prereqs = 0;
+my @missing_prereqs = ();
 if ($ENV{SLIC3R_NO_AUTO}) {
     foreach my $module (sort keys %prereqs) {
         my $version = $prereqs{$module};
         next if eval "use $module $version; 1";
-        $missing_prereqs = 1 if exists $prereqs{$module};
+        push @missing_prereqs = $module if exists $prereqs{$module};
         print "Missing prerequisite $module $version\n";
     }
     foreach my $module (sort keys %recommends) {
@@ -102,7 +103,7 @@ EOF
         my $res = system $cpanm, "$module~$version";
         if ($res != 0) {
             if (exists $prereqs{$module}) {
-                $missing_prereqs = 1;
+                push @missing_prereqs, $module;
             } else {
                 printf "Don't worry, this module is optional.\n";
             }
@@ -129,15 +130,15 @@ EOF
     }
 }
 
-if ($missing_prereqs) {
+if (@missing_prereqs) {
+    printf "The following prerequisites failed to install: %s\n", join(', ', @missing_prereqs);
     exit 1;
-} else {
-    my $res = 0;
-    if (eval "use App::Prove; 1") {
-        $res = App::Prove->new->run ? 0 : 1;
-    }
-    if (!$gui) {
+} elsif (!$gui) {
+    my $res = App::Prove->new->run ? 0 : 1;
+    if ($res == 0) {
         print "If you also want to use the GUI you can now run `perl Build.PL --gui` to install the required modules.\n";
+    } else {
+        print "Some tests failed. Please report the failure to the author!\n";
     }
     exit $res;
 }