diff --git a/pub/lib/commands.cpp b/pub/lib/commands.cpp
index 0d00c59753c575c756b301fd877d401cb7335db8..0ee6f3212bbfc5c9713472a7c2f88681c127baa0 100644
--- a/pub/lib/commands.cpp
+++ b/pub/lib/commands.cpp
@@ -307,7 +307,7 @@ bool frida_command(string cmd)
                 "  gd   graphic dialog (feed commands to gnuplot)\n"
                 "Save for print:\n"
                 "  gp   plot to complete .ps file\n"
-                "  gf   plot to short .psX file\n"
+                "  gf   plot to short .psa file\n"
                 "  gfa  append plot to existing .ps or .psa file\n"
                 "Change window:\n"
                 "  gw   list of plot windows\n"
diff --git a/pub/lib/import.cpp b/pub/lib/import.cpp
index 03af1968d7958aa14708659370de0ef80365c557..5f324de876c6f5483187b9561cacf88ae8c5fdeb 100644
--- a/pub/lib/import.cpp
+++ b/pub/lib/import.cpp
@@ -183,7 +183,7 @@ void NImport::read_tab(string qualif)
                     if (dat.size() != (with_d ? 3 : 2)) {
                         throw "line " + S(n_in) + " (line " + S(nline) + " in block " + S(nblock)
                             + ") [" + lin + "] contains " + S(dat.size()) + " values; "
-                            + "at present, exactly " + S(with_d ? 3 : 2) + " are required";
+                            + " exactly " + S(with_d ? 3 : 2) + " are required";
                     }
                     if (with_d)
                         s->push_xy(dat[0], dat[1]);
diff --git a/pub/plot/dualplot.cpp b/pub/plot/dualplot.cpp
index 46c0feb7b7fec2cbdf887ec96681af555a0b0637..f1d144ae016c28ca260bb48ce4fc26ba7d78d053 100644
--- a/pub/plot/dualplot.cpp
+++ b/pub/plot/dualplot.cpp
@@ -341,7 +341,7 @@ void CPlot::write_postscript(
     if (!triv::file_exists(fname))
         throw "BUG: after copying headers, graphic output file " + fname + " still doesn't exist";
     if (!(pssav = fopen(fname.c_str(), mode=="append" ? "a" : "w")))
-        throw "cannot append contents to file " + fname;
+        throw "BUG: cannot open file " + fname;
     for (string lin : ps_accu) {
         // fprintf does not work here because output line may contain "%"
         fwrite(lin.c_str(), 1, lin.size(), pssav);