diff --git a/src/core/system_parameters/gnss_satellite.cc b/src/core/system_parameters/gnss_satellite.cc
index c2b2516fd..7a13616e1 100644
--- a/src/core/system_parameters/gnss_satellite.cc
+++ b/src/core/system_parameters/gnss_satellite.cc
@@ -391,7 +391,7 @@ std::string Gnss_Satellite::what_block(const std::string& system_, uint32_t PRN_
                     block_ = std::string("IIF");  // Plane C
                     break;
                 case 28:
-                    block_ = std::string("IIR");  // Plane B
+                    block_ = std::string("III");  // Plane B
                     break;
                 case 29:
                     block_ = std::string("IIR-M");  // Plane C