diff --git a/sys/include/shell.h b/sys/include/shell.h
index ed2e617767..f2587ddc0c 100644
--- a/sys/include/shell.h
+++ b/sys/include/shell.h
@@ -34,6 +34,8 @@ typedef struct shell_t {
     void (*put_char)(int);
 } shell_t;
 
+#define SHELL_BUFFER_SIZE (127)
+
 /**
  * @brief Initialize a shell object
  * @param shell Pointer to preallocated shell object
diff --git a/sys/shell/shell.c b/sys/shell/shell.c
index 20689c0251..2339222238 100644
--- a/sys/shell/shell.c
+++ b/sys/shell/shell.c
@@ -92,9 +92,10 @@ static void print_help(const shell_command_t *command_list)
 
 static void handle_input_line(shell_t *shell, char *line)
 {
+    char line_copy[SHELL_BUFFER_SIZE];
     char *saveptr;
-    char *linedup = strdup(line);
-    char *command = strtok_r(linedup, " ", &saveptr);
+    strncpy(line_copy, line, sizeof(line_copy));
+    char *command = strtok_r(line_copy, " ", &saveptr);
 
     void (*handler)(char *) = NULL;
 
@@ -113,8 +114,6 @@ static void handle_input_line(shell_t *shell, char *line)
             }
         }
     }
-
-    free(linedup);
 }
 
 static int readline(shell_t *shell, char *buf, size_t size)
@@ -155,7 +154,7 @@ static inline void print_prompt(shell_t *shell)
 
 void shell_run(shell_t *shell)
 {
-    char line_buf[255];
+    char line_buf[SHELL_BUFFER_SIZE];
 
     print_prompt(shell);
 
@@ -163,9 +162,7 @@ void shell_run(shell_t *shell)
         int res = readline(shell, line_buf, sizeof(line_buf));
 
         if (!res) {
-            char *line_copy = strdup(line_buf);
-            handle_input_line(shell, line_copy);
-            free(line_copy);
+            handle_input_line(shell, line_buf);
         }
 
         print_prompt(shell);