diff --git a/ppp/pam_ppp.c b/ppp/pam_ppp.c
index b1cca18..2183628 100644
--- a/ppp/pam_ppp.c
+++ b/ppp/pam_ppp.c
@@ -83,6 +83,9 @@ int pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc, const char **ar
 		goto cleanup;
 	}
 	
+	/* Reserve the passcode the user will have to type */
+	reservePasscodeNum();
+	
 	struct pam_conv *conversation;
 	struct pam_message message;
 	struct pam_message *pmessage = &message;
diff --git a/ppp/ppp.c b/ppp/ppp.c
index 66b233b..ad5b3ac 100644
--- a/ppp/ppp.c
+++ b/ppp/ppp.c
@@ -77,6 +77,9 @@ static int nRounds = 0;
 
 static mp_int d_seqKey;
 static mp_int d_currPasscodeNum;
+static mp_int d_reservedPasscodeNum;
+static char d_reserved;
+
 static mp_int d_lastCardGenerated;
 static mp_int d_maxPasscodes;
 static char d_passcode[5] = "";
@@ -276,6 +279,7 @@ static void _compute_passcode_block(mp_int *cipherNum, mp_int *cipherBlock) {
 void pppInit() {
 	mp_init(&d_seqKey);
 	mp_init(&d_currPasscodeNum);
+	d_reserved = 0;
 	mp_init(&d_lastCardGenerated);
 	
 	/* Here, we compute the maximum number of passcodes handle by this
@@ -362,13 +366,13 @@ char *currCode() {
 	mp_init(&mp);
 	mp_init(&row);
 
-	calculateCardContainingPasscode(currPasscodeNum(), &mp);
+	calculateCardContainingPasscode(currAuthPasscodeNum(), &mp);
 	mp_add_d(&mp, 1, &mp);
 	char *cardstr = mpToDecimalString(&mp, ',');
 	mp_sub_d(&mp, 1, &mp);
 	
 	mp_mul_d(&mp, 70, &row);
-	mp_sub(currPasscodeNum(), &row, &row);
+	mp_sub(currAuthPasscodeNum(), &row, &row);
 	mp_set_int(&mp, 7);
 	mp_div(&row, &mp, &row, &mp);
 	_mp_to_uint(&row, &r);
@@ -394,18 +398,33 @@ char *currPrompt() {
 	return d_prompt;
 }
 
+
 int pppAuthenticate(const char *attempt) {
 	int rv = 0;
-	if (strcmp(getPasscode(currPasscodeNum()), attempt) == 0) {
+
+	if (strcmp(getPasscode(currAuthPasscodeNum()), attempt) == 0) {
 		rv = 1;
-		incrCurrPasscodeNum();
-		writeState();
-	} else {
-		if ( ! pppCheckFlags(PPP_DONT_SKIP_ON_FAILURES)) {
+		if (!d_reserved) {
+			/* Increment now, wasn't incremented before */
 			incrCurrPasscodeNum();
 			writeState();
 		}
+	} else {
+		if ( ! pppCheckFlags(PPP_DONT_SKIP_ON_FAILURES)) {
+			if (!d_reserved) {
+				/* Increment now */
+				incrCurrPasscodeNum();
+				writeState();
+			}
+		} else {
+			if (d_reserved) {
+				/* Was reserved, but failed and should be decreased... */
+				decrCurrPasscodeNum();
+				writeState();
+			}
+		}
 	}
+	d_reserved = 0;
 	
 	_zero_bytes((unsigned char *)d_passcode, 5);
 	
@@ -440,7 +459,7 @@ int pppWarning(char *buf, int size) {
 				"  more passcodes IMMEDIATELY so you can continue to log\n"
 				"  into your account.\n"
 				"@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@\n",
-				mpToDecimalString(&mp, NULL), (mp_cmp_d(&mp, 1) ? "s":"")
+				mpToDecimalString(&mp, 0), (mp_cmp_d(&mp, 1) ? "s":"")
 			);
 		}
 		break;
@@ -489,11 +508,22 @@ void setSeqKey(mp_int *mp) {
 	mp_copy(mp, &d_seqKey);
 }
 
+mp_int *currAuthPasscodeNum() {
+	/* Return passcode which must be used for authentication */
+	if (d_reserved) {
+		return &d_reservedPasscodeNum;
+	} else {
+		return &d_currPasscodeNum;
+	}
+}
+
 mp_int *currPasscodeNum() {
+	/* Return passcode */
 	return &d_currPasscodeNum;
 }
 
-void setCurrPasscodeNum(mp_int *mp) {
+
+void setCurrPasscodeNum(const mp_int *mp) {
 	mp_copy(mp, &d_currPasscodeNum);
 }
 
@@ -505,6 +535,21 @@ void incrCurrPasscodeNum() {
 	mp_add_d(&d_currPasscodeNum, 1, &d_currPasscodeNum);
 }
 
+void decrCurrPasscodeNum() {
+	mp_sub_d(&d_currPasscodeNum, 1, &d_currPasscodeNum);
+}
+
+
+void reservePasscodeNum(void) {
+	mp_copy(&d_currPasscodeNum, &d_reservedPasscodeNum);
+	d_reserved = 1;
+
+	/* Increment num, so parallel sessions won't reserve the same passCode */
+	/* FIXME: Races should be fixed by some lock file */
+	incrCurrPasscodeNum();
+	writeState(); 
+} 
+
 mp_int *lastCardGenerated() {
 	return &d_lastCardGenerated;
 }
diff --git a/ppp/ppp.h b/ppp/ppp.h
index ab49fdf..04f215d 100644
--- a/ppp/ppp.h
+++ b/ppp/ppp.h
@@ -55,9 +55,13 @@ int pppWarning(char *buf, int size);
 mp_int *seqKey();
 void setSeqKey(mp_int *mp);
 mp_int *currPasscodeNum();
-void setCurrPasscodeNum(mp_int *mp);
+mp_int *currAuthPasscodeNum();
+void setCurrPasscodeNum(const mp_int *mp);
 void zeroCurrPasscodeNum();
 void incrCurrPasscodeNum();
+void decrCurrPasscodeNum();
+void reservePasscodeNum(void);
+mp_int *reservedPasscodeNum(void);
 mp_int *lastCardGenerated();
 void setLastCardGenerated(mp_int *mp);
 void zeroLastCardGenerated();