diff --git a/src/interpreter/vmx.c b/src/interpreter/vmx.c
index 28d19c5f..8beb0240 100644
--- a/src/interpreter/vmx.c
+++ b/src/interpreter/vmx.c
@@ -1,6 +1,13 @@
 #include "pocketpy/interpreter/vm.h"
 #include <assert.h>
 
+// importing io.h for tty detection in replinput
+#if defined(_WIN32) || defined(_WIN64)
+#include <io.h>
+#elif defined(__linux__) || defined(__APPLE__) || defined(__ANDROID__)
+#include <unistd.h>
+#endif
+
 void pk_print_stack(VM* self, py_Frame* frame, Bytecode byte) {
     return;
     if(frame == NULL || !self->main || py_isnil(self->main)) return;
@@ -66,12 +73,20 @@ bool pk_wrapper__self(int argc, py_Ref argv) {
     return true;
 }
 
+// macro for tty-sensitiveness
+#if defined(_WIN32) || defined(_WIN64)
+#define istty(fd) _isatty(_fileno(fd))
+#elif defined(__linux__) || defined(__APPLE__) || defined(__ANDROID__)
+#define istty(fd) isatty(fileno(fd))
+#else
+#define istty(fd) 1 
+#endif
 int py_replinput(char* buf, int max_size) {
     buf[0] = '\0';  // reset first char because we check '@' at the beginning
 
     int size = 0;
     bool multiline = false;
-    printf(">>> ");
+    if (istty(stdin)) printf(">>> ");
 
     while(true) {
         int c = pk_current_vm->callbacks.getchr();
@@ -107,6 +122,7 @@ int py_replinput(char* buf, int max_size) {
     buf[size] = '\0';
     return size;
 }
+#undef istty
 
 py_Ref py_name2ref(py_Name name) {
     assert(name != NULL);
diff --git a/src2/main.c b/src2/main.c
index 4212293b..453585b7 100644
--- a/src2/main.c
+++ b/src2/main.c
@@ -9,6 +9,16 @@
 #include <windows.h>
 #endif
 
+#if defined(_WIN32) || defined(_WIN64)
+#include <io.h>
+#define istty(fd) _isatty(_fileno(fd))
+#elif defined(__linux__) || defined(__APPLE__) || defined(__ANDROID__)
+#include <unistd.h>
+#define istty(fd) isatty(fileno(fd))
+#else
+#define istty(fd) 1 
+#endif
+
 static char* readfile(const char* path, int* data_size) {
     FILE* f = fopen(path, "rb");
     if(f == NULL) return NULL;
@@ -86,19 +96,21 @@ int main(int argc, char** argv) {
         if(profile) printf("Warning: --profile is ignored in REPL mode.\n");
         if(debug) printf("Warning: --debug is ignored in REPL mode.\n");
 
-        printf("pocketpy " PK_VERSION " (" __DATE__ ", " __TIME__ ") ");
-        printf("[%d bit] on %s", (int)(sizeof(void*) * 8), PY_SYS_PLATFORM_STRING);
+        if (istty(stdin)) {
+            printf("pocketpy " PK_VERSION " (" __DATE__ ", " __TIME__ ") ");
+            printf("[%d bit] on %s", (int)(sizeof(void*) * 8), PY_SYS_PLATFORM_STRING);
 #ifndef NDEBUG
-        printf(" (DEBUG)");
+            printf(" (DEBUG)");
 #endif
-        printf("\n");
-        printf("https://github.com/pocketpy/pocketpy\n");
-        printf("Type \"exit()\" to exit.\n");
+            printf("\n");
+            printf("https://github.com/pocketpy/pocketpy\n");
+            printf("Type \"exit()\" to exit.\n");
+        }
 
         while(true) {
             int size = py_replinput(buf, sizeof(buf));
             if(size == -1) {  // Ctrl-D (i.e. EOF)
-                printf("\n");
+                if (istty(stdin)) printf("\n");
                 break;
             }
             assert(size < sizeof(buf));
@@ -160,3 +172,4 @@ int main(int argc, char** argv) {
     if(debug) py_debugger_exit(code);
     return code;
 }
+#undef istty
\ No newline at end of file