diff --git a/src/sums.d b/src/sums.d
index 48101a1..983b566 100644
--- a/src/sums.d
+++ b/src/sums.d
@@ -21,11 +21,30 @@ import std.file : isDir;
 import std.conv;
 import std.string;
 import tiger;
+import std.exception;
+import std.format;
+import std.array : appender;
+
+private void writeError (string parFile, string parMessage) {
+	stderr.writefln("tigersum: %s: %s", parFile, parMessage);
+}
+
+private void writeWarning (string parMessage) {
+	writeError("WARNING", parMessage);
+}
 
 void calculateSums (in string[] parFiles, in string parCWD, bool parTiger2, string parFileMode, bool parBsdStyle) {
 	foreach (file_name; parFiles) {
 		const auto curr_path = parCWD ~ file_name;
-		File curr_file = File(curr_path, parFileMode);
+		File curr_file;
+		try {
+			curr_file = File(curr_path, parFileMode);
+		}
+		catch (ErrnoException err) {
+			writeError(file_name, "unexisting file or directory");
+			continue;
+		}
+
 		if (!isDir(curr_path)) {
 			const string hash = tigerToString(getTiger(curr_file, parTiger2));
 			if (parBsdStyle) {
@@ -36,7 +55,7 @@ void calculateSums (in string[] parFiles, in string parCWD, bool parTiger2, stri
 			}
 		}
 		else {
-			writefln("tigersum: %s: is a directory", file_name);
+			writeError(file_name, "is a directory");
 		}
 	}
 }
@@ -46,6 +65,9 @@ bool checkSums (in string parFile, in string parCWD, bool parTiger2, string parF
 	bool ret_val = true;
 	const auto reg_bsd = r"^tiger \((.+)\)\s*=\s*([a-fA-F0-9]{48})$";
 	const auto reg_normal = r"^([a-fA-F0-9]{48})\s+(.+)$";
+	int unmatched_lines;
+	int mismatches;
+	int failed_open;
 
 	foreach (line; curr_list.byLine()) {
 		auto m = match(line, reg_bsd);
@@ -65,14 +87,45 @@ bool checkSums (in string parFile, in string parCWD, bool parTiger2, string parF
 			writef("%s: ", capt_filename);
 
 			const string curr_path = parCWD ~ capt_filename;
-			File curr_file = File(curr_path, parFileMode);
+			File curr_file;
+			try {
+				curr_file = File(curr_path, parFileMode);
+			}
+			catch (ErrnoException err) {
+				++failed_open;
+				writeln("opening or reading FAILED");
+				writeError(capt_filename, "unexisting file or directory");
+				continue;
+			}
 			const string curr_tiger = tigerToString(getTiger(curr_file, parTiger2));
 			const string check_tiger = to!string(m.captures[index_hash]).toLower;
-			if (check_tiger == curr_tiger)
+			if (check_tiger == curr_tiger) {
 				writeln("OK");
-			else
+			}
+			else {
+				++mismatches;
 				writeln("FAILED");
+			}
 		}
+		else {
+			++unmatched_lines;
+		}
+	}
+
+	if (unmatched_lines) {
+		auto writer = appender!string();
+		formattedWrite(writer, "%d line%s not formatted correctly", unmatched_lines, (unmatched_lines == 1 ? "" : "s"));
+		writeWarning(writer.data);
+	}
+	if (failed_open) {
+		auto writer = appender!string();
+		formattedWrite(writer, "%d listed file%s can't be read", failed_open, (failed_open == 1 ? "" : "s"));
+		writeWarning(writer.data);
+	}
+	if (mismatches) {
+		auto writer = appender!string();
+		formattedWrite(writer, "%d calculated checksum%s match", mismatches, (mismatches == 1 ? " DOESN'T" : "s DON'T"));
+		writeWarning(writer.data);
 	}
 	return ret_val;
 }