diff --git a/MIR.md b/MIR.md
index 1f682f491b..3f697e35d2 100644
--- a/MIR.md
+++ b/MIR.md
@@ -19,7 +19,7 @@
    * To start work with MIR program, you should first call API function `MIR_init`
    * API function `MIR_finish (MIR_context_t ctx)` should be called last.  It frees all internal data used to work with MIR program and all IR (insns, functions, items, and modules) created in this context
    * API function `MIR_output (MIR_context_t ctx, FILE *f)` outputs MIR textual representation of the program into given file
-   * API function `MIR_scan_string (MIR_context_t ctx, const char *str)` reads textual MIR representation given by a string
+   * API function `MIR_scan_string_s (MIR_context_t ctx, const char *str, size_t str_len)` reads textual MIR representation given by a string
    * API functions `MIR_write (MIR_context_t ctx, FILE *f)` and
      `MIR_read (MIR_context_t ctx, FILE *f)` outputs and reads
      **binary MIR representation** to/from given file.  There are also
diff --git a/mir.c b/mir.c
index 20034721b2..34521d5294 100644
--- a/mir.c
+++ b/mir.c
@@ -5267,6 +5267,7 @@ struct scan_ctx {
   HTAB (insn_name_t) * insn_name_tab;
   const char *input_string;
   size_t input_string_char_num;
+  size_t input_string_char_limit;
   VARR (label_name_t) * label_names;
   HTAB (label_desc_t) * label_desc_tab;
 };
@@ -5280,6 +5281,7 @@ struct scan_ctx {
 #define insn_name_tab ctx->scan_ctx->insn_name_tab
 #define input_string ctx->scan_ctx->input_string
 #define input_string_char_num ctx->scan_ctx->input_string_char_num
+#define input_string_char_limit ctx->scan_ctx->input_string_char_limit
 #define label_names ctx->scan_ctx->label_names
 #define label_desc_tab ctx->scan_ctx->label_desc_tab
 
@@ -5457,8 +5459,8 @@ static void scan_string (MIR_context_t ctx, token_t *t, int c, int get_char (MIR
 }
 
 static int get_string_char (MIR_context_t ctx) {
+  if (input_string_char_num >= input_string_char_limit) return EOF;
   int ch = input_string[input_string_char_num];
-
   if (ch == '\0') return EOF;
   input_string_char_num++;
   if (ch == '\n') curr_lno++;
@@ -5640,7 +5642,12 @@ static MIR_type_t str2type (const char *type_name) {
 
 */
 
+void MIR_scan_string_s (MIR_context_t ctx, const char *str, size_t str_len);
 void MIR_scan_string (MIR_context_t ctx, const char *str) {
+  MIR_scan_string_s(ctx, str, SIZE_MAX);
+}
+
+void MIR_scan_string_s (MIR_context_t ctx, const char *str, size_t str_len) {
   token_t t;
   const char *name;
   MIR_module_t module = NULL;
@@ -5660,6 +5667,7 @@ void MIR_scan_string (MIR_context_t ctx, const char *str) {
   curr_lno = 1;
   input_string = str;
   input_string_char_num = 0;
+  input_string_char_limit = str_len;
   t.code = TC_NL;
   for (;;) {
     if (setjmp (error_jmp_buf)) {
diff --git a/mir.h b/mir.h
index 820397b06a..d806d199bb 100644
--- a/mir.h
+++ b/mir.h
@@ -581,7 +581,9 @@ extern void MIR_read_with_func (MIR_context_t ctx, int (*const reader_func) (MIR
 #endif
 
 #if !MIR_NO_SCAN
+/** deprecated: use MIR_scan_string_s */
 extern void MIR_scan_string (MIR_context_t ctx, const char *str);
+extern void MIR_scan_string_s (MIR_context_t ctx, const char *str, size_t str_len);
 #endif
 
 extern MIR_item_t MIR_get_global_item (MIR_context_t ctx, const char *name);