diff --git a/include/fort.h b/include/fort.h
index 5790ab8..f0093aa 100644
--- a/include/fort.h
+++ b/include/fort.h
@@ -524,7 +524,7 @@ FT_EXTERN int ft_set_default_cell_option(uint32_t option, int value);
  *   - 0: Success; cell option was changed.
  *   - (-1): !!!!!!!!  todo
  */
-FT_EXTERN int ft_set_cell_option(FTABLE *table, unsigned row, unsigned col, uint32_t option, int value);
+FT_EXTERN int ft_set_cell_option(FTABLE *table, size_t row, size_t col, uint32_t option, int value);
 
 /**
  * Table options identifiers
diff --git a/src/cell.c b/src/cell.c
index 057bd1c..edef0ca 100644
--- a/src/cell.c
+++ b/src/cell.c
@@ -36,7 +36,7 @@ void destroy_cell(fort_cell_t *cell)
     F_FREE(cell);
 }
 
-unsigned int hint_width_cell(const fort_cell_t *cell, const context_t *context)
+size_t hint_width_cell(const fort_cell_t *cell, const context_t *context)
 {
     /* todo:
      * At the moment min width includes paddings. Maybe it is better that min width weren't include
@@ -45,24 +45,24 @@ unsigned int hint_width_cell(const fort_cell_t *cell, const context_t *context)
 
     assert(cell);
     assert(context);
-    unsigned int cell_padding_left = get_cell_opt_value_hierarcial(context->table_options, context->row, context->column, FT_COPT_LEFT_PADDING);
-    unsigned int cell_padding_right = get_cell_opt_value_hierarcial(context->table_options, context->row, context->column, FT_COPT_RIGHT_PADDING);
-    unsigned int result = cell_padding_left + cell_padding_right;
+    size_t cell_padding_left = get_cell_opt_value_hierarcial(context->table_options, context->row, context->column, FT_COPT_LEFT_PADDING);
+    size_t cell_padding_right = get_cell_opt_value_hierarcial(context->table_options, context->row, context->column, FT_COPT_RIGHT_PADDING);
+    size_t result = cell_padding_left + cell_padding_right;
     if (cell->str_buffer && cell->str_buffer->str.data) {
         result += buffer_text_width(cell->str_buffer);
     }
-    result = MAX(result, (unsigned)get_cell_opt_value_hierarcial(context->table_options, context->row, context->column, FT_COPT_MIN_WIDTH));
+    result = MAX(result, (size_t)get_cell_opt_value_hierarcial(context->table_options, context->row, context->column, FT_COPT_MIN_WIDTH));
     return result;
 }
 
-unsigned int hint_height_cell(const fort_cell_t *cell, const context_t *context)
+size_t hint_height_cell(const fort_cell_t *cell, const context_t *context)
 {
     assert(cell);
     assert(context);
-    unsigned int cell_padding_top = get_cell_opt_value_hierarcial(context->table_options, context->row, context->column, FT_COPT_TOP_PADDING);
-    unsigned int cell_padding_bottom = get_cell_opt_value_hierarcial(context->table_options, context->row, context->column, FT_COPT_BOTTOM_PADDING);
-    unsigned int cell_empty_string_height = get_cell_opt_value_hierarcial(context->table_options, context->row, context->column, FT_COPT_EMPTY_STR_HEIGHT);
-    int result = cell_padding_top + cell_padding_bottom;
+    size_t cell_padding_top = get_cell_opt_value_hierarcial(context->table_options, context->row, context->column, FT_COPT_TOP_PADDING);
+    size_t cell_padding_bottom = get_cell_opt_value_hierarcial(context->table_options, context->row, context->column, FT_COPT_BOTTOM_PADDING);
+    size_t cell_empty_string_height = get_cell_opt_value_hierarcial(context->table_options, context->row, context->column, FT_COPT_EMPTY_STR_HEIGHT);
+    size_t result = cell_padding_top + cell_padding_bottom;
     if (cell->str_buffer && cell->str_buffer->str.data) {
         size_t text_height = buffer_text_height(cell->str_buffer);
         result += text_height == 0 ? cell_empty_string_height : text_height;
diff --git a/src/cell.h b/src/cell.h
index 45bc0b9..b7d768f 100644
--- a/src/cell.h
+++ b/src/cell.h
@@ -13,8 +13,8 @@ fort_cell_t * create_cell(void);
 
 
 void destroy_cell(fort_cell_t *cell);
-unsigned int hint_width_cell(const fort_cell_t *cell, const context_t *context);
-unsigned int hint_height_cell(const fort_cell_t *cell, const context_t *context);
+size_t hint_width_cell(const fort_cell_t *cell, const context_t *context);
+size_t hint_height_cell(const fort_cell_t *cell, const context_t *context);
 
 
 /*
diff --git a/src/fort.c b/src/fort.c
index 1a262ea..5273a49 100644
--- a/src/fort.c
+++ b/src/fort.c
@@ -824,7 +824,7 @@ int ft_set_border_style(FTABLE *table, struct ft_border_style *style)
 
 
 
-int ft_set_cell_option(FTABLE *table, unsigned row, unsigned col, uint32_t option, int value)
+int ft_set_cell_option(FTABLE *table, size_t row, size_t col, uint32_t option, int value)
 {
     assert(table);
 
diff --git a/src/fort_impl.c b/src/fort_impl.c
index 1f44471..001f834 100644
--- a/src/fort_impl.c
+++ b/src/fort_impl.c
@@ -148,6 +148,10 @@ int snprint_n_chars(char *buf, size_t length, size_t n, char ch)
     if (n == 0)
         return 0;
 
+    /* To ensure valid return value it is safely not print such big strings */
+    if (n > INT_MAX)
+        return -1;
+
     int status = snprintf(buf, length, "%0*d", (int)n, 0);
     if (status < 0)
         return status;
@@ -157,7 +161,7 @@ int snprint_n_chars(char *buf, size_t length, size_t n, char ch)
         *buf = ch;
         buf++;
     }
-    return n;
+    return (int)n;
 }
 
 
@@ -169,6 +173,10 @@ int wsnprint_n_chars(wchar_t *buf, size_t length, size_t n, wchar_t ch)
     if (n == 0)
         return 0;
 
+    /* To ensure valid return value it is safely not print such big strings */
+    if (n > INT_MAX)
+        return -1;
+
     int status = swprintf(buf, length, L"%0*d", (int)n, 0);
     if (status < 0)
         return status;
@@ -178,5 +186,5 @@ int wsnprint_n_chars(wchar_t *buf, size_t length, size_t n, wchar_t ch)
         *buf = ch;
         buf++;
     }
-    return n;
+    return (int)n;
 }
diff --git a/src/fort_impl.h b/src/fort_impl.h
index 89d10d9..8e692f8 100644
--- a/src/fort_impl.h
+++ b/src/fort_impl.h
@@ -1,6 +1,10 @@
 #ifndef FORT_IMPL_H
 #define FORT_IMPL_H
 
+#if defined(_MSC_VER)
+#define _CRT_SECURE_NO_WARNINGS /* To disable warnings for unsafe functions */
+#endif
+
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
@@ -8,9 +12,7 @@
 #include <stdio.h>
 #include "fort.h"
 
-#if defined(FT_MICROSOFT_COMPILER)
-#define _CRT_SECURE_NO_WARNINGS /* To disable warnings for unsafe functions */
-#endif
+
 
 #define FORT_COL_SEPARATOR '|'
 
diff --git a/src/options.c b/src/options.c
index ed3426e..8a4d402 100644
--- a/src/options.c
+++ b/src/options.c
@@ -86,7 +86,7 @@ void destroy_cell_opt_container(fort_cell_opt_container_t *cont)
         destroy_vector(cont);
 }
 
-const fort_cell_options_t *cget_cell_opt(const fort_cell_opt_container_t *cont, unsigned row, unsigned col)
+const fort_cell_options_t *cget_cell_opt(const fort_cell_opt_container_t *cont, size_t row, size_t col)
 {
     assert(cont);
     size_t sz = vector_size(cont);
@@ -99,7 +99,7 @@ const fort_cell_options_t *cget_cell_opt(const fort_cell_opt_container_t *cont,
     return NULL;
 }
 
-fort_cell_options_t *get_cell_opt_and_create_if_not_exists(fort_cell_opt_container_t *cont, unsigned row, unsigned col)
+fort_cell_options_t *get_cell_opt_and_create_if_not_exists(fort_cell_opt_container_t *cont, size_t row, size_t col)
 {
     assert(cont);
     size_t sz = vector_size(cont);
@@ -186,7 +186,7 @@ fort_fail:
 }
 
 
-fort_status_t set_cell_option(fort_cell_opt_container_t *cont, unsigned row, unsigned col, uint32_t option, int value)
+fort_status_t set_cell_option(fort_cell_opt_container_t *cont, size_t row, size_t col, uint32_t option, int value)
 {
     fort_cell_options_t *opt = get_cell_opt_and_create_if_not_exists(cont, row, col);
     if (opt == NULL)
diff --git a/src/options.h b/src/options.h
index b08a1d9..aab23a4 100644
--- a/src/options.h
+++ b/src/options.h
@@ -26,8 +26,8 @@ typedef struct vector vector_t;
 
 struct fort_cell_options
 {
-    unsigned cell_row;
-    unsigned cell_col;
+    size_t cell_row;
+    size_t cell_col;
     uint32_t options;
     unsigned int col_min_width;
     enum ft_text_alignment align;
@@ -46,9 +46,9 @@ typedef struct fort_cell_options fort_cell_options_t;
 typedef vector_t fort_cell_opt_container_t;
 fort_cell_opt_container_t *create_cell_opt_container(void);
 void destroy_cell_opt_container(fort_cell_opt_container_t *cont);
-const fort_cell_options_t* cget_cell_opt(const fort_cell_opt_container_t *cont, unsigned row, unsigned col);
-fort_cell_options_t* get_cell_opt_and_create_if_not_exists(fort_cell_opt_container_t *cont, unsigned row, unsigned col);
-fort_status_t set_cell_option(fort_cell_opt_container_t *cont, unsigned row, unsigned col, uint32_t option, int value);
+const fort_cell_options_t* cget_cell_opt(const fort_cell_opt_container_t *cont, size_t row, size_t col);
+fort_cell_options_t* get_cell_opt_and_create_if_not_exists(fort_cell_opt_container_t *cont, size_t row, size_t col);
+fort_status_t set_cell_option(fort_cell_opt_container_t *cont, size_t row, size_t col, uint32_t option, int value);
 fort_status_t unset_cell_option(fort_cell_opt_container_t *cont, unsigned row, unsigned col, uint32_t option);
 
 int get_cell_opt_value_hierarcial(const fort_table_options_t *options, size_t row, size_t column, uint32_t option);
diff --git a/src/row.c b/src/row.c
index dff3468..422b6ef 100644
--- a/src/row.c
+++ b/src/row.c
@@ -52,7 +52,7 @@ void destroy_row(fort_row_t *row)
 
 
 
-unsigned int columns_in_row(const fort_row_t *row)
+size_t columns_in_row(const fort_row_t *row)
 {
     if (row == NULL || row->cells == NULL)
         return 0;
@@ -414,7 +414,7 @@ fort_row_t *create_row_from_fmt_string(const char  *fmt, va_list *va_args)
     while (1) {
         va_list va;
         va_copy(va, *va_args);
-        int virtual_sz = vsnprintf(buffer->str.cstr, string_buffer_capacity(buffer)/*buffer->str_sz*/, fmt, va);
+        int virtual_sz = vsnprintf(buffer->str.cstr, string_buffer_capacity(buffer), fmt, va);
         va_end(va);
         /* If error encountered */
         if (virtual_sz < 0)
@@ -463,7 +463,7 @@ int snprintf_row(const fort_row_t *row, char *buffer, size_t buf_sz, size_t *col
     if (row == NULL)
         return -1;
 
-    unsigned int cols_in_row = columns_in_row(row);
+    size_t cols_in_row = columns_in_row(row);
     if (cols_in_row > col_width_arr_sz)
         return -1;
 
@@ -533,7 +533,7 @@ int wsnprintf_row(const fort_row_t *row, wchar_t *buffer, size_t buf_sz, size_t
     if (row == NULL)
         return -1;
 
-    unsigned int cols_in_row = columns_in_row(row);
+    size_t cols_in_row = columns_in_row(row);
     if (cols_in_row > col_width_arr_sz)
         return -1;
 
diff --git a/src/row.h b/src/row.h
index bec125d..68f3701 100644
--- a/src/row.h
+++ b/src/row.h
@@ -24,7 +24,7 @@ fort_row_t * create_row_from_string(const char *str);
 fort_row_t* create_row_from_fmt_string(const char*  fmt, va_list *va_args);
 
 
-unsigned int columns_in_row(const fort_row_t *row);
+size_t columns_in_row(const fort_row_t *row);
 
 fort_cell_t *get_cell_implementation(fort_row_t *row, size_t col, enum PolicyOnNull policy);
 fort_cell_t *get_cell(fort_row_t *row, size_t col);
diff --git a/src/string_buffer.c b/src/string_buffer.c
index 97f662a..bb98bbf 100644
--- a/src/string_buffer.c
+++ b/src/string_buffer.c
@@ -3,18 +3,21 @@
 #include "assert.h"
 #include "wchar.h"
 #include "wcwidth.h"
+#include <stddef.h>
 /*****************************************************************************
  *               STRING BUFFER
  * ***************************************************************************/
 
 
-static int str_iter_width(const char *beg, const char *end)
+static ptrdiff_t str_iter_width(const char *beg, const char *end)
 {
-    return end - beg;
+    assert(end >= beg);
+    return (end - beg);
 }
 
-static int wcs_iter_width(const wchar_t *beg, const wchar_t *end)
+static ptrdiff_t wcs_iter_width(const wchar_t *beg, const wchar_t *end)
 {
+    assert(end >= beg);
     return mk_wcswidth(beg, (end - beg));
 }
 
@@ -293,8 +296,8 @@ int buffer_printf(string_buffer_t *buffer, size_t buffer_row, char *buf, size_t
     if ((buf_len - 1) < content_width)
         return -1;
 
-    int left = 0;
-    int right = 0;
+    size_t left = 0;
+    size_t right = 0;
 
     switch (get_cell_opt_value_hierarcial(context->table_options, context->row, context->column, FT_COPT_TEXT_ALIGN)) {
         case FT_ALIGNED_LEFT:
@@ -313,9 +316,6 @@ int buffer_printf(string_buffer_t *buffer, size_t buffer_row, char *buf, size_t
             assert(0);
             break;
     }
-    if (left < 0 || right < 0)
-        return -1;
-
 
     int  written = 0;
     int tmp = 0;
@@ -331,9 +331,13 @@ int buffer_printf(string_buffer_t *buffer, size_t buffer_row, char *buf, size_t
     old_value = *end;
     *(CHAR_TYPE *)end = NULL_CHAR;
 
+    ptrdiff_t str_it_width = STR_ITER_WIDTH(beg, end);
+    if (str_it_width < 0 || content_width < (size_t)str_it_width)
+        return - 1;
+
     CHCK_RSLT_ADD_TO_WRITTEN(SNPRINTF(buf + written, buf_len - written, SNPRINTF_FMT_STR, (int)(end - beg), beg));
     *(CHAR_TYPE *)end = old_value;
-    CHCK_RSLT_ADD_TO_WRITTEN(SNPRINT_N_CHARS(buf + written,  buf_len - written, (int)(content_width - STR_ITER_WIDTH(beg, end)), SPACE_CHAR));
+    CHCK_RSLT_ADD_TO_WRITTEN(SNPRINT_N_CHARS(buf + written,  buf_len - written, (content_width - (size_t)str_it_width), SPACE_CHAR));
     CHCK_RSLT_ADD_TO_WRITTEN(SNPRINT_N_CHARS(buf + written, buf_len - written, right, SPACE_CHAR));
     return written;
 
@@ -375,8 +379,8 @@ int buffer_wprintf(string_buffer_t *buffer, size_t buffer_row, wchar_t *buf, siz
     if ((buf_len - 1) < content_width)
         return -1;
 
-    int left = 0;
-    int right = 0;
+    size_t left = 0;
+    size_t right = 0;
 
     switch (get_cell_opt_value_hierarcial(context->table_options, context->row, context->column, FT_COPT_TEXT_ALIGN)) {
         case FT_ALIGNED_LEFT:
@@ -395,8 +399,6 @@ int buffer_wprintf(string_buffer_t *buffer, size_t buffer_row, wchar_t *buf, siz
             assert(0);
             break;
     }
-    if (left < 0 || right < 0)
-        return -1;
 
     int  written = 0;
     int tmp = 0;
@@ -412,9 +414,13 @@ int buffer_wprintf(string_buffer_t *buffer, size_t buffer_row, wchar_t *buf, siz
     old_value = *end;
     *(CHAR_TYPE *)end = NULL_CHAR;
 
+    ptrdiff_t str_it_width = STR_ITER_WIDTH(beg, end);
+    if (str_it_width < 0 || content_width < (size_t)str_it_width)
+        return - 1;
+
     CHCK_RSLT_ADD_TO_WRITTEN(SNPRINTF(buf + written, buf_len - written, SNPRINTF_FMT_STR, (int)(end - beg), beg));
     *(CHAR_TYPE *)end = old_value;
-    CHCK_RSLT_ADD_TO_WRITTEN(SNPRINT_N_CHARS(buf + written,  buf_len - written, (int)(content_width - STR_ITER_WIDTH(beg, end)), SPACE_CHAR));
+    CHCK_RSLT_ADD_TO_WRITTEN(SNPRINT_N_CHARS(buf + written,  buf_len - written, (content_width - (size_t)str_it_width), SPACE_CHAR));
     CHCK_RSLT_ADD_TO_WRITTEN(SNPRINT_N_CHARS(buf + written, buf_len - written, right, SPACE_CHAR));
     return written;