diff --git a/main.cpp b/main.cpp
index 5c48f830..4a6a2894 100644
--- a/main.cpp
+++ b/main.cpp
@@ -6,12 +6,14 @@
 #define SIMPLECPP_TOKENLIST_ALLOW_PTR 0
 #include "simplecpp.h"
 
+#include <cstdint>
 #include <cstdlib>
 #include <cstring>
 #include <fstream>
 #include <iostream>
-#include <sys/stat.h>
+#include <sstream>
 #include <string>
+#include <sys/stat.h>
 #include <utility>
 #include <vector>
 
@@ -28,7 +30,12 @@ int main(int argc, char **argv)
 {
     bool error = false;
     const char *filename = nullptr;
-    bool use_istream = false;
+    enum : std::uint8_t {
+        File,
+        Fstream,
+        Sstream,
+        CharBuffer
+    } toklist_inf = File;
     bool fail_on_error = false;
     bool linenrs = false;
 
@@ -86,9 +93,28 @@ int main(int argc, char **argv)
                         break;
                     }
                     dui.includes.emplace_back(std::move(value));
-                } else if (std::strcmp(arg, "-is")==0) {
+                }
+                else if (std::strncmp(arg, "-input=",7)==0) {
                     found = true;
-                    use_istream = true;
+                    const std::string input = arg + 7;
+                    if (input.empty()) {
+                        std::cout << "error: option -inout with no value." << std::endl;
+                        error = true;
+                        break;
+                    }
+                    if (input == "file") {
+                        toklist_inf = File;
+                    } else if (input == "fstream") {
+                        toklist_inf = Fstream;
+                    } else if (input == "sstream") {
+                        toklist_inf = Sstream;
+                    } else if (input == "buffer") {
+                        toklist_inf = CharBuffer;
+                    } else {
+                        std::cout << "error: unknown input type '" << input << "'." << std::endl;
+                        error = true;
+                        break;
+                    }
                 }
                 break;
             case 's':
@@ -117,8 +143,8 @@ int main(int argc, char **argv)
                 break;
             case 'f':
                 if (std::strcmp(arg, "-f")==0) {
-                    found = true;
                     fail_on_error = true;
+                    found = true;
                 }
                 break;
             case 'l':
@@ -157,7 +183,7 @@ int main(int argc, char **argv)
         std::cout << "  -UNAME          Undefine NAME." << std::endl;
         std::cout << "  -std=STD        Specify standard." << std::endl;
         std::cout << "  -q              Quiet mode (no output)." << std::endl;
-        std::cout << "  -is             Use std::istream interface." << std::endl;
+        std::cout << "  -input=INPUT    Specify input type - file (default), fstream, sstream, buffer." << std::endl;
         std::cout << "  -e              Output errors only." << std::endl;
         std::cout << "  -f              Fail when errors were encountered (exitcode 1)." << std::endl;
         std::cout << "  -l              Print lines numbers." << std::endl;
@@ -197,8 +223,21 @@ int main(int argc, char **argv)
     simplecpp::TokenList outputTokens(files);
     {
         simplecpp::TokenList *rawtokens;
-        if (use_istream) {
-            rawtokens = new simplecpp::TokenList(f, files,filename,&outputList);
+        if (toklist_inf == Fstream) {
+            rawtokens = new simplecpp::TokenList(f,files,filename,&outputList);
+        }
+        else if (toklist_inf == Sstream || toklist_inf == CharBuffer) {
+            std::ostringstream oss;
+            oss << f.rdbuf();
+            f.close();
+            const std::string s = oss.str();
+            if (toklist_inf == Sstream) {
+                std::istringstream iss(s);
+                rawtokens = new simplecpp::TokenList(iss,files,filename,&outputList);
+            }
+            else {
+                rawtokens = new simplecpp::TokenList({s.data(),s.size()},files,filename,&outputList);
+            }
         } else {
             f.close();
             rawtokens = new simplecpp::TokenList(filename,files,&outputList);