diff --git a/src/Makefile b/src/Makefile
index c74ba0b..b07ff04 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -38,7 +38,7 @@ LIBS += -L. -lgmp -lmpfr -lm
 
 # objects
 PQC_OBJS = poly.o mem.o encrypt.o decrypt.o keypair.o ascii_poly.o
-PQC_HEADERS = err.h poly.h context.h encrypt.h decrypt.h keypair.h ascii_poly.h
+PQC_HEADERS = err.h poly.h context.h encrypt.h decrypt.h keypair.h ascii_poly.h common.h
 # CUNIT_OBJS = cunit.o
 
 # includes
diff --git a/src/ascii_poly.c b/src/ascii_poly.c
index 3e05649..d4c793c 100644
--- a/src/ascii_poly.c
+++ b/src/ascii_poly.c
@@ -19,6 +19,7 @@
  * MA  02110-1301  USA
  */
 
+#include "common.h"
 #include "context.h"
 #include "mem.h"
 #include "poly.h"
@@ -49,15 +50,14 @@ static char *get_bin_arr_to_ascii(char *binary_rep);
 static char *get_int_to_bin_str(uint8_t value)
 {
     int i;
-	const size_t ascii_bit_size = 8;
-	const size_t bin_string_size = ascii_bit_size + 1;
-	char *bin_string = ntru_malloc(sizeof(char) *
+	const size_t bin_string_size = ASCII_BITS + 1;
+	char *bin_string = ntru_malloc(sizeof(*bin_string) *
 			(bin_string_size)); /* account for trailing null-byte */
 
 	/* terminate properly */
     bin_string[bin_string_size - 1] = '\0';
 
-    for (i = 7; i >= 0; --i, value >>= 1)
+    for (i = ASCII_BITS - 1; i >= 0; --i, value >>= 1)
         bin_string[i] = (value & 1) + '0';
 
 	return bin_string;
@@ -84,7 +84,7 @@ static char *get_bin_arr_to_ascii(char *binary_rep)
 
 	while (*tmp_string) {
 		int_arr[i] = 0;
-		for (uint32_t j = 0; j < 8; j++) {
+		for (uint32_t j = 0; j < ASCII_BITS; j++) {
 			if (*tmp_string == '1')
 				int_arr[i] = int_arr[i] * 2 + 1;
 			else if (*tmp_string == '0')
@@ -94,7 +94,7 @@ static char *get_bin_arr_to_ascii(char *binary_rep)
 		i++;
 	}
 
-	int_string = ntru_calloc(1, sizeof(char) * (i + 1));
+	int_string = ntru_calloc(1, CHAR_SIZE * (i + 1));
 
 	for (uint32_t j = 0; j < i; j++)
 		int_string[j] = (char) int_arr[j];
@@ -114,7 +114,7 @@ fmpz_poly_t **ascii_to_poly(char *to_poly, ntru_context *ctx)
 	uint32_t i = 0,
 			 polyc = 0;
 	char *cur = to_poly;
-	size_t out_size = sizeof(char) * (strlen(to_poly) * 8 + 1);
+	size_t out_size = CHAR_SIZE * (strlen(to_poly) * 8 + 1);
 	char *out = ntru_malloc(out_size);
 	fmpz_poly_t **poly_array;
 
@@ -171,9 +171,9 @@ char *poly_to_ascii(fmpz_poly_t **poly_array, ntru_context *ctx)
 	/*
 	 * parse the polynomial coefficients into a string
 	 */
-	binary_rep = ntru_malloc(sizeof(char) * (ctx->N + 1));
+	binary_rep = ntru_malloc(CHAR_SIZE * (ctx->N + 1));
 	while ((ascii_poly = *poly_array++)) {
-		new_length = sizeof(char) * (ctx->N + 1);
+		new_length = CHAR_SIZE * (ctx->N + 1);
 
 		REALLOC(binary_rep,
 				old_length +
diff --git a/src/common.h b/src/common.h
new file mode 100644
index 0000000..d8dc4d0
--- /dev/null
+++ b/src/common.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2014 FH Bielefeld
+ *
+ * This file is part of a FH Bielefeld project.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA  02110-1301  USA
+ */
+
+/**
+ * @file common.h
+ * This file holds common macros and functions
+ * shared throughout the whole codebase without
+ * any particular purpose.
+ * @brief common macros/functions
+ */
+
+#ifndef NTRU_COMMON_H
+#define NTRU_COMMON_H
+
+
+#define CHAR_SIZE sizeof(char)
+#define ASCII_BITS 8
+
+
+#endif /* NTRU_COMMON_H */