diff --git a/src/HomeSpan.cpp b/src/HomeSpan.cpp
index 9a0991f..d0612f2 100644
--- a/src/HomeSpan.cpp
+++ b/src/HomeSpan.cpp
@@ -1645,6 +1645,13 @@ int SpanCharacteristic::sprintfAttributes(char *cBuf, int flags){
         nBytes+=snprintf(cBuf?(cBuf+nBytes):NULL,cBuf?128:0,",\"minStep\":%s",uvPrint(stepValue).c_str());
     }
 
+    if(unit){
+      if(strlen(unit)>0)
+        nBytes+=snprintf(cBuf?(cBuf+nBytes):NULL,cBuf?128:0,",\"unit\":\"%s\"",unit);
+     else
+        nBytes+=snprintf(cBuf?(cBuf+nBytes):NULL,cBuf?128:0,",\"unit\":null");
+    }
+
     if(validValues){
       nBytes+=snprintf(cBuf?(cBuf+nBytes):NULL,cBuf?128:0,",\"valid-values\":%s",validValues);      
     }
diff --git a/src/HomeSpan.h b/src/HomeSpan.h
index 40f872a..3a3f39c 100644
--- a/src/HomeSpan.h
+++ b/src/HomeSpan.h
@@ -260,6 +260,7 @@ struct SpanCharacteristic{
   uint8_t perms;                           // Characteristic Permissions
   FORMAT format;                           // Characteristic Format        
   char *desc=NULL;                         // Characteristic Description (optional)
+  char *unit=NULL;                         // Characteristic Unit (optional)
   UVal minValue;                           // Characteristic minimum (not applicable for STRING)
   UVal maxValue;                           // Characteristic maximum (not applicable for STRING)
   UVal stepValue;                          // Characteristic step size (not applicable for STRING)
@@ -607,6 +608,12 @@ struct SpanCharacteristic{
     return(this);
   }  
 
+  SpanCharacteristic *setUnit(const char *c){
+    unit = (char *)realloc(unit, strlen(c) + 1);
+    strcpy(unit, c);
+    return(this);
+  }  
+
 };
 
 ///////////////////////////////