diff --git a/main/main.cpp b/main/main.cpp
index 6369a25..08db475 100644
--- a/main/main.cpp
+++ b/main/main.cpp
@@ -241,18 +241,20 @@ int main(int argc, char **argv)
         cerr << "  A time map (or key-frame map) file contains a series of lines, each with two" << endl;
         cerr << "  sample frame numbers separated by a single space. These are source and" << endl;
         cerr << "  target frames for fixed time points within the audio data, defining a varying" << endl;
-        cerr << "  stretch factor through the audio. When supplying a time map, you must specify" << endl;
-        cerr << "  an overall stretch factor using -t, -T, or -D as well." << endl;
+        cerr << "  stretch factor through the audio. When supplying a time map you must specify" << endl;
+        cerr << "  an overall stretch factor using -t, -T, or -D as well, to determine the" << endl;
+        cerr << "  total output duration." << endl;
         cerr << endl;
         cerr << "         --pitchmap <F>   Use file F as the source for pitch map" << endl;
         cerr << endl;
-        cerr << "  A pitch map file contains a series of lines, each with two values: a" << endl;
+        cerr << "  A pitch map file contains a series of lines, each with two values: the input" << endl;
         cerr << "  sample frame number and a pitch offset in semitones, separated by a single" << endl;
         cerr << "  space. These specify a varying pitch factor through the audio. The offsets" << endl;
         cerr << "  are all relative to an initial offset specified by the pitch or frequency" << endl;
         cerr << "  option, or relative to no shift if neither was specified. Offsets are" << endl;
         cerr << "  not cumulative. This option implies realtime mode (-R) and also enables a" << endl;
         cerr << "  high-consistency pitch shifting mode, appropriate for dynamic pitch changes." << endl;
+        cerr << "  Because of the use of realtime mode, the overall duration will not be exact." << endl;
         cerr << endl;
         cerr << "         --freqmap <F>    Use file F as the source for frequency map" << endl;
         cerr << endl;