diff --git a/main.cpp b/main.cpp
index e622f51..6d5a5d1 100644
--- a/main.cpp
+++ b/main.cpp
@@ -93,7 +93,7 @@ int handleParams(int argc, const char **argv)
        ("in-text-file,i", po::value<string>(&params.inTextFile)->required(), "input text file path (positional arg 1)")
        ("in-pattern-file,I", po::value<string>(&params.inPatternFile)->required(), "input pattern file path (positional arg 2)")
        ("approx,k", po::value<int>(&params.kApprox), "perform approximate search (Hamming distance) for k errors (preliminary, max pattern length = 12)")
-       ("out-file,o", po::value<string>(&params.outFile), "output file path")
+       ("out-file,o", po::value<string>(&params.outFile)->default_value("res.txt"), "output file path")
        ("pattern-count,p", po::value<int>(&params.nPatterns), "maximum number of patterns read from top of the patterns file (non-positive values are ignored)")
        ("version,v", "display version info");
 
diff --git a/params.hpp b/params.hpp
index 84afd73..7837a30 100644
--- a/params.hpp
+++ b/params.hpp
@@ -33,12 +33,12 @@ struct Params
     int nPatterns = noValue;
 
     /** Input text file path (positional arg 1). */
-    std::string inTextFile = "";
+    std::string inTextFile;
     /** Input pattern file path (positional arg 2). */
-    std::string inPatternFile = "";
+    std::string inPatternFile;
 
     /** Output file path. */
-    std::string outFile = "res.txt";
+    std::string outFile;
 
     /*
      *** CONSTANTS