diff --git a/src/convrnx.c b/src/convrnx.c
index dd71a02143627aeb43172ee42e08270ea30b7100..2292cbdaf99c2a75cfa91dc330b08da4beeafcf0 100644
--- a/src/convrnx.c
+++ b/src/convrnx.c
@@ -432,8 +432,8 @@ static void sort_codes(unsigned char *codes, unsigned char *types, int n)
     int i,j;
     
     for (i=0;i<n-1;i++) for (j=i+1;j<n;j++) {
-       obs1=code2obs(NULL,codes[i],NULL);
-       obs2=code2obs(NULL,codes[j],NULL);
+       obs1=code2obs(0,codes[i],NULL);
+       obs2=code2obs(0,codes[j],NULL);
        if (strcmp(obs1,obs2)<=0) continue;
        tmp=codes[i]; codes[i]=codes[j]; codes[j]=tmp;
        tmp=types[i]; types[i]=types[j]; types[j]=tmp;
@@ -664,7 +664,7 @@ static int scan_obstype(int format, char **files, int nf, rnxopt_t *opt,
         return 0;
     }
     for (i=0;i<NSATSYS;i++) for (j=0;j<n[i];j++) {
-        trace(2,"scan_obstype: sys=%d code=%s type=%d\n",i,code2obs(NULL,codes[i][j],NULL),types[i][j]);
+        trace(2,"scan_obstype: sys=%d code=%s type=%d\n",i,code2obs(0,codes[i][j],NULL),types[i][j]);
     }
     for (i=0;i<NSATSYS;i++) {
         
@@ -675,7 +675,7 @@ static int scan_obstype(int format, char **files, int nf, rnxopt_t *opt,
         setopt_obstype(codes[i],types[i],i,opt);
         
         for (j=0;j<n[i];j++) {
-            trace(3,"scan_obstype: sys=%d code=%s\n",i,code2obs(NULL,codes[i][j],NULL));
+            trace(3,"scan_obstype: sys=%d code=%s\n",i,code2obs(0,codes[i][j],NULL));
         }
     }
     return 1;
diff --git a/src/rinex.c b/src/rinex.c
index c60835e3cac3c4b7d73c45437a5d9d58f840b18c..acefce571c499ad00cb4d31ac790b20c48e75d1a 100644
--- a/src/rinex.c
+++ b/src/rinex.c
@@ -903,7 +903,7 @@ static void set_index(double ver, int sys, const char *opt,
     for (p=opt;p&&(p=strchr(p,'-'));p++) {
         if (sscanf(p,optstr,str,&shift)<2) continue;
         for (i=0;i<n;i++) {
-            if (strcmp(code2obs(NULL,ind->code[i],NULL),str)) continue;
+            if (strcmp(code2obs(0,ind->code[i],NULL),str)) continue;
             ind->shift[i]=shift;
             trace(2,"phase shift: sys=%2d tobs=%s shift=%.3f\n",sys,
                   tobs[i],shift);
@@ -2078,12 +2078,12 @@ static int obsindex(double ver, int sys, const unsigned char *code,
                     return i;
             }
             else {
-                id=code2obs(NULL,code[i],NULL);
+                id=code2obs(0,code[i],NULL);
                 if (id[0]==tobs[1]) return i;
             }
         }
         else { /* ver.3 */
-            id=code2obs(NULL,code[i],NULL);
+            id=code2obs(0,code[i],NULL);
             if (!strcmp(id,tobs+1)) return i;
         }
     }