diff --git a/emory/chunk/params.hpp b/emory/chunk/params.hpp
index f0bfed6..2dd4e06 100644
--- a/emory/chunk/params.hpp
+++ b/emory/chunk/params.hpp
@@ -19,4 +19,10 @@ namespace emory::chunk {
         /// The minimum number of bytes for a matching region.
         std::ptrdiff_t minimum;
     };
+
+    constexpr params DEFAULT_PARAMS {
+        .bits    =   12,
+        .window  =    8,
+        .minimum = 4096,
+    };
 }
diff --git a/tools/analyse.cpp b/tools/analyse.cpp
index 98a3140..ce15b64 100644
--- a/tools/analyse.cpp
+++ b/tools/analyse.cpp
@@ -69,32 +69,27 @@ enum {
 };
 
 
-static constexpr std::size_t DEFAULT_BITS    =  12;
-static constexpr std::size_t DEFAULT_WINDOW  =   4;
-static constexpr std::ptrdiff_t DEFAULT_MINIMUM = 512;
-
-
 //-----------------------------------------------------------------------------
 int main (int argc, char const **argv)
 {
     if (argc < NUM_ARGS_REQUIRED) {
         std::cerr << "usage: " << argv[ARG_SELF] << " <input> <output> [bits] [window] [minimum]\n"
-                  << "default bits = "    << DEFAULT_BITS    << '\n'
-                  << "default window = "  << DEFAULT_WINDOW  << '\n'
-                  << "default minimum = " << DEFAULT_MINIMUM << '\n';
+                  << "default bits = "    << emory::chunk::DEFAULT_PARAMS.bits    << '\n'
+                  << "default window = "  << emory::chunk::DEFAULT_PARAMS.window  << '\n'
+                  << "default minimum = " << emory::chunk::DEFAULT_PARAMS.minimum << '\n';
         return EXIT_FAILURE;
     }
 
-    #define PARSE_DEFAULT(NAME, TYPE)                           \
-    argc > ARG_##NAME                                           \
-        ? cruft::parse::from_string<TYPE> (argv[ARG_##NAME])    \
-        : DEFAULT_##NAME
+    emory::chunk::params p = emory::chunk::DEFAULT_PARAMS;
+    if (argc > ARG_BITS)
+        p.window = cruft::parse::from_string<std::size_t> (argv[ARG_WINDOW]);
+    if (argc > ARG_WINDOW)
+        p.window = cruft::parse::from_string<std::size_t> (argv[ARG_BITS]);
+    if (argc > ARG_BITS)
+        p.minimum = cruft::parse::from_string<std::size_t> (argv[ARG_MINIMUM]);
+
+    std::cerr << p << '\n';
 
-    emory::chunk::params const p {
-        .bits    = PARSE_DEFAULT (BITS, std::size_t),
-        .window  = PARSE_DEFAULT (WINDOW, std::size_t),
-        .minimum = PARSE_DEFAULT (MINIMUM, std::ptrdiff_t),
-    };
 
     cruft::mapped_file data (argv[ARGS_INPUT]);
     std::cout << "size: " << data.size () << '\n';