diff --git a/src/modules/Si443x/Si443x.cpp b/src/modules/Si443x/Si443x.cpp
index c498622f..f7e81576 100644
--- a/src/modules/Si443x/Si443x.cpp
+++ b/src/modules/Si443x/Si443x.cpp
@@ -554,9 +554,10 @@ int16_t Si443x::setDataShaping(uint8_t sh) {
     case RADIOLIB_SHAPING_NONE:
       return(_mod->SPIsetRegValue(RADIOLIB_SI443X_REG_MODULATION_MODE_CONTROL_1, RADIOLIB_SI443X_MANCHESTER_INVERTED_OFF | RADIOLIB_SI443X_MANCHESTER_OFF | RADIOLIB_SI443X_WHITENING_OFF, 2, 0));
     case RADIOLIB_SHAPING_0_3:
+      return(RADIOLIB_ERR_INVALID_ENCODING);
     case RADIOLIB_SHAPING_0_5:
+      return(_mod->SPIsetRegValue(RADIOLIB_SI443X_REG_MODULATION_MODE_CONTROL_2, RADIOLIB_SI443X_MODULATION_GFSK, 1, 0));
     case RADIOLIB_SHAPING_1_0:
-      /// \todo implement fiter configuration - docs claim this should be possible, but seems undocumented
       return(_mod->SPIsetRegValue(RADIOLIB_SI443X_REG_MODULATION_MODE_CONTROL_1, RADIOLIB_SI443X_MANCHESTER_INVERTED_OFF | RADIOLIB_SI443X_MANCHESTER_OFF | RADIOLIB_SI443X_WHITENING_ON, 2, 0));
     default:
       return(RADIOLIB_ERR_INVALID_ENCODING);
diff --git a/src/modules/Si443x/Si443x.h b/src/modules/Si443x/Si443x.h
index 1ee97a12..cf4f689b 100644
--- a/src/modules/Si443x/Si443x.h
+++ b/src/modules/Si443x/Si443x.h
@@ -777,7 +777,7 @@ class Si443x: public PhysicalLayer {
 
     /*!
       \brief Sets Gaussian filter bandwidth-time product that will be used for data shaping. Only available in FSK mode with FSK modulation.
-      Allowed values are RADIOLIB_SHAPING_0_3, RADIOLIB_SHAPING_0_5 or RADIOLIB_SHAPING_1_0. Set to RADIOLIB_SHAPING_NONE to disable data shaping.
+      Allowed values are RADIOLIB_SHAPING_0_5 or RADIOLIB_SHAPING_1_0. Set to RADIOLIB_SHAPING_NONE to disable data shaping.
 
       \param sh Gaussian shaping bandwidth-time product that will be used for data shaping