diff --git a/src/gsm/a5.c b/src/gsm/a5.c
index e330c75..34f271a 100644
--- a/src/gsm/a5.c
+++ b/src/gsm/a5.c
@@ -89,10 +89,10 @@
 #define A5_R3_MASK	((1<<A5_R3_LEN)-1)
 #define A5_R4_MASK	((1<<A5_R4_LEN)-1)
 
-#define A5_R1_TAPS	0x072000 /* x^19 + x^5 + x^2 + x + 1 */
-#define A5_R2_TAPS	0x300000 /* x^22 + x + 1 */
-#define A5_R3_TAPS	0x700080 /* x^23 + x^15 + x^2 + x + 1 */
-#define A5_R4_TAPS	0x010800 /* x^17 + x^5 + 1 */
+#define A5_R1_TAPS	0x072000 /* x^19 + x^18 + x^17 + x^14 + 1 */
+#define A5_R2_TAPS	0x300000 /* x^22 + x^21 + 1 */
+#define A5_R3_TAPS	0x700080 /* x^23 + x^22 + x^21 + x^8 + 1 */
+#define A5_R4_TAPS	0x010800 /* x^17 + x^12 + 1 */
 
 /*! \brief Computes parity of a 32-bit word
  *  \param[in] x 32 bit word