diff --git a/src/algorithms/libs/rtklib/rtklib.h b/src/algorithms/libs/rtklib/rtklib.h
index 117a1b26f..379e75b75 100644
--- a/src/algorithms/libs/rtklib/rtklib.h
+++ b/src/algorithms/libs/rtklib/rtklib.h
@@ -186,18 +186,15 @@ const int MAXPRNGAL = 36;                         //!<   max satellite PRN numbe
 const int NSATGAL = (MAXPRNGAL - MINPRNGAL + 1);  //!<   number of Galileo satellites
 const int NSYSGAL = 1;
 
+const int MAXPRNQZS = 199;  //!<   max satellite PRN number of QZSS
+const int MINPRNQZS = 193;  //!<   min satellite PRN number of QZSS
 #ifdef ENAQZS
-const int MINPRNQZS = 193;                        //!<  min satellite PRN number of QZSS
-const int MAXPRNQZS = 199;                        //!<   max satellite PRN number of QZSS
 const int MINPRNQZS_S = 183;                      //!<   min satellite PRN number of QZSS SAIF
 const int MAXPRNQZS_S = 189;                      //!<   max satellite PRN number of QZSS SAIF
 const int NSATQZS = (MAXPRNQZS - MINPRNQZS + 1);  //!<   number of QZSS satellites
 const int NSYSQZS = 1;
 #else
-const int MINPRNQZS = 0;
-const int MAXPRNQZS = 0;
 const int MINPRNQZS_S = 0;
-const int MAXPRNQZS_S = 0;
 const int NSATQZS = 0;
 const int NSYSQZS = 0;
 #endif
@@ -215,26 +212,22 @@ const int NSATBDS = 0;
 const int NSYSBDS = 0;
 #endif
 
+const int MINPRNIRN = 1;  //!<   min satellite sat number of IRNSS
+const int MAXPRNIRN = 7;  //!<   max satellite sat number of IRNSS
 #ifdef ENAIRN
-const int MINPRNIRN = 1;                          //!<   min satellite sat number of IRNSS
-const int MAXPRNIRN = 7;                          //!<  max satellite sat number of IRNSS
 const int NSATIRN = (MAXPRNIRN - MINPRNIRN + 1);  //!<   number of IRNSS satellites
 const int NSYSIRN = 1;
 #else
-const int MINPRNIRN = 0;
-const int MAXPRNIRN = 0;
 const int NSATIRN = 0;
 const int NSYSIRN = 0;
 #endif
 
+const int MINPRNLEO = 1;   //!<   min satellite sat number of LEO
+const int MAXPRNLEO = 10;  //!<   max satellite sat number of LEO */
 #ifdef ENALEO
-const int MINPRNLEO = 1;                          //!<   min satellite sat number of LEO
-const int NSATLEO = 10;                           //!<   max satellite sat number of LEO
 const int NSATLEO = (MAXPRNLEO - MINPRNLEO + 1);  //!<   number of LEO satellites
 const int NSYSLEO = 1;
 #else
-const int MINPRNLEO = 0;
-const int MAXPRNLEO = 0;
 const int NSATLEO = 0;
 const int NSYSLEO = 0;
 #endif
diff --git a/src/algorithms/libs/rtklib/rtklib_rtkcmn.cc b/src/algorithms/libs/rtklib/rtklib_rtkcmn.cc
index 3385d6c92..b5304dcdb 100644
--- a/src/algorithms/libs/rtklib/rtklib_rtkcmn.cc
+++ b/src/algorithms/libs/rtklib/rtklib_rtkcmn.cc
@@ -274,19 +274,19 @@ int satno(int sys, int prn)
                 }
             return NSATGPS + NSATGLO + NSATGAL + prn - MINPRNQZS + 1;
         case SYS_BDS:
-            if (prn < MINPRNBDS || MAXPRNBDS < prn)
+            if (MAXPRNBDS < prn)
                 {
                     return 0;
                 }
             return NSATGPS + NSATGLO + NSATGAL + NSATQZS + prn - MINPRNBDS + 1;
         case SYS_IRN:
-            if (prn < MINPRNIRN || MAXPRNIRN < prn)
+            if (MAXPRNIRN < prn)
                 {
                     return 0;
                 }
             return NSATGPS + NSATGLO + NSATGAL + NSATQZS + NSATBDS + prn - MINPRNIRN + 1;
         case SYS_LEO:
-            if (prn < MINPRNLEO || MAXPRNLEO < prn)
+            if (MAXPRNLEO < prn)
                 {
                     return 0;
                 }
@@ -378,7 +378,7 @@ int satsys(int sat, int *prn)
 int satid2no(const char *id)
 {
     int sys;
-    int prn = 0;
+    int prn;
     char code;
 
     if (sscanf(id, "%d", &prn) == 1)
@@ -443,6 +443,11 @@ int satid2no(const char *id)
         default:
             return 0;
         }
+    if (prn <= 0 || prn > MAXSAT)
+        {
+            return 0;
+        }
+
     return satno(sys, prn);
 }