diff --git a/tool/util.c b/tool/util.c
index 0a7f615..1bdc184 100644
--- a/tool/util.c
+++ b/tool/util.c
@@ -57,23 +57,6 @@ FILE *open_file(const char *file_name, int mode) {
   return file;
 }
 
-bool input_ready(FILE *file) {
-  int fd = fileno(file);
-  fd_set rfds;
-  struct timeval tv;
-
-  FD_ZERO(&rfds);
-  FD_SET(fd, &rfds);
-
-  tv.tv_sec = 0;
-  tv.tv_usec = 0;
-
-  if(select(fd + 1, &rfds, NULL, NULL, &tv) == 1) {
-    return true;
-  }
-  return false;
-}
-
 unsigned char get_algorithm(EVP_PKEY *key) {
   int type = EVP_PKEY_type(key->type);
   switch(type) {
diff --git a/tool/util.h b/tool/util.h
index 307cd9e..9ad2051 100644
--- a/tool/util.h
+++ b/tool/util.h
@@ -45,6 +45,5 @@ unsigned char get_algorithm(EVP_PKEY*);
 FILE *open_file(const char*, int);
 int get_object_id(enum enum_slot slot);
 bool set_component_with_len(unsigned char**, const BIGNUM*, int);
-bool input_ready(FILE*);
 
 #endif
diff --git a/tool/yubico-piv-tool.c b/tool/yubico-piv-tool.c
index e92fc9b..cbffa86 100644
--- a/tool/yubico-piv-tool.c
+++ b/tool/yubico-piv-tool.c
@@ -33,6 +33,7 @@
 #include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <unistd.h>
 
 #include "ykpiv.h"
 
@@ -290,7 +291,7 @@ static bool import_key(ykpiv_state *state, enum enum_key_format key_format,
     return false;
   }
 
-  if(input_file == stdin && !input_ready(input_file)) {
+  if(isatty(fileno(input_file))) {
     fprintf(stderr, "Please paste the private key...\n");
   }
 
@@ -416,7 +417,7 @@ static bool import_cert(ykpiv_state *state, enum enum_key_format cert_format,
     return false;
   }
 
-  if(input_file == stdin && !input_ready(input_file)) {
+  if(isatty(fileno(input_file))) {
     fprintf(stderr, "Please paste the certificate...\n");
   }
 
@@ -563,7 +564,7 @@ static bool request_certificate(ykpiv_state *state, enum enum_key_format key_for
     goto request_out;
   }
 
-  if(input_file == stdin && !input_ready(input_file)) {
+  if(isatty(fileno(input_file))) {
     fprintf(stderr, "Please paste the public key...\n");
   }
 
@@ -746,7 +747,7 @@ static bool selfsign_certificate(ykpiv_state *state, enum enum_key_format key_fo
     goto selfsign_out;
   }
 
-  if(input_file == stdin && !input_ready(input_file)) {
+  if(isatty(fileno(input_file))) {
     fprintf(stderr, "Please paste the public key...\n");
   }
 
@@ -1023,7 +1024,7 @@ static bool sign_file(ykpiv_state *state, const char *input, const char *output,
     return false;
   }
 
-  if(input_file == stdin && !input_ready(input_file)) {
+  if(isatty(fileno(input_file))) {
     fprintf(stderr, "Please paste the input...\n");
   }