--- pigpio-44/pigpio.c
+++ pigpio-44/pigpio.c
@@ -6269,7 +6269,7 @@
                tp->id,
               (unsigned)tp->nextTick.tv_sec,
               (unsigned)tp->nextTick.tv_nsec);
-            fprintf(stderr, buf);
+            fprintf(stderr, "%s", buf);
          }
       }
 
@@ -6360,7 +6360,7 @@
                   break;
 
                case 5:
-                  fprintf(outFifo, cmdUsage);
+                  fprintf(outFifo, "%s", cmdUsage);
                   break;
 
                case 6: