diff --git a/fluid/shell_command.cxx b/fluid/shell_command.cxx
index 97c49f462..a6c49c823 100644
--- a/fluid/shell_command.cxx
+++ b/fluid/shell_command.cxx
@@ -365,7 +365,7 @@ void shell_pipe_cb(FL_SOCKET, void*) {
 static void expand_macro(std::string &cmd, const std::string &macro, const std::string &content) {
   for (int i=0;;) {
     i = cmd.find(macro, i);
-    if (i==std::string::npos) break;
+    if (i==(int)std::string::npos) break;
     cmd.replace(i, macro.size(), content);
   }
 }
diff --git a/src/Fl_Native_File_Chooser_Kdialog.cxx b/src/Fl_Native_File_Chooser_Kdialog.cxx
index 18f6b9d03..75c5e6050 100644
--- a/src/Fl_Native_File_Chooser_Kdialog.cxx
+++ b/src/Fl_Native_File_Chooser_Kdialog.cxx
@@ -312,7 +312,7 @@ const char *Fl_Kdialog_Native_File_Chooser_Driver::title() const {
 //
 void Fl_Kdialog_Native_File_Chooser_Driver::shell_quote(Fl_String& s) {
   Fl_String out = "'";                          // leading quote
-  for (int t=0; t<s.size(); t++) {
+  for (int t=0; t<(int)s.size(); t++) {
     if (s[t] == '\'') out += "'\"'\"'";         // quote any quotes
     else              out += s[t];
   }
diff --git a/src/drivers/Unix/Fl_Unix_System_Driver.cxx b/src/drivers/Unix/Fl_Unix_System_Driver.cxx
index 3c7907bcc..58064a90a 100644
--- a/src/drivers/Unix/Fl_Unix_System_Driver.cxx
+++ b/src/drivers/Unix/Fl_Unix_System_Driver.cxx
@@ -555,10 +555,10 @@ char *Fl_Unix_System_Driver::preference_user_rootnode(
     if (prefs_path_14.find("~/")==0) // starts with "~"
       prefs_path_14.replace(0, 1, home_path);
     int h_env = prefs_path_14.find("${HOME}");
-    if (h_env!=prefs_path_14.npos)
+    if (h_env!=(int)prefs_path_14.npos)
       prefs_path_14.replace(h_env, 7, home_path);
     h_env = prefs_path_14.find("$HOME/");
-    if (h_env!=prefs_path_14.npos)
+    if (h_env!=(int)prefs_path_14.npos)
       prefs_path_14.replace(h_env, 5, home_path);
   }
   if (prefs_path_14[prefs_path_14.size()-1]!='/')