diff --git a/hardware/arduino/avr/cores/arduino/Stream.cpp b/hardware/arduino/avr/cores/arduino/Stream.cpp
index d2846316d34..17e96e986a6 100644
--- a/hardware/arduino/avr/cores/arduino/Stream.cpp
+++ b/hardware/arduino/avr/cores/arduino/Stream.cpp
@@ -139,7 +139,7 @@ long Stream::parseInt(LookaheadMode lookahead, char ignore)
     return 0; // zero returned if timeout
 
   do{
-    if(c == ignore)
+    if((char)c == ignore)
       ; // ignore this character
     else if(c == '-')
       isNegative = true;
@@ -148,7 +148,7 @@ long Stream::parseInt(LookaheadMode lookahead, char ignore)
     read();  // consume the character we got with peek
     c = timedPeek();
   }
-  while( (c >= '0' && c <= '9') || c == ignore );
+  while( (c >= '0' && c <= '9') || (char)c == ignore );
 
   if(isNegative)
     value = -value;
@@ -170,7 +170,7 @@ float Stream::parseFloat(LookaheadMode lookahead, char ignore)
     return 0; // zero returned if timeout
 
   do{
-    if(c == ignore)
+    if((char)c == ignore)
       ; // ignore
     else if(c == '-')
       isNegative = true;
@@ -184,7 +184,7 @@ float Stream::parseFloat(LookaheadMode lookahead, char ignore)
     read();  // consume the character we got with peek
     c = timedPeek();
   }
-  while( (c >= '0' && c <= '9')  || (c == '.' && !isFraction) || c == ignore );
+  while( (c >= '0' && c <= '9')  || (c == '.' && !isFraction) || (char)c == ignore );
 
   if(isNegative)
     value = -value;
@@ -222,7 +222,7 @@ size_t Stream::readBytesUntil(char terminator, char *buffer, size_t length)
   size_t index = 0;
   while (index < length) {
     int c = timedRead();
-    if (c < 0 || c == terminator) break;
+    if (c < 0 || (char)c == terminator) break;
     *buffer++ = (char)c;
     index++;
   }
@@ -245,7 +245,7 @@ String Stream::readStringUntil(char terminator)
 {
   String ret;
   int c = timedRead();
-  while (c >= 0 && c != terminator)
+  while (c >= 0 && (char)c != terminator)
   {
     ret += (char)c;
     c = timedRead();
@@ -268,7 +268,7 @@ int Stream::findMulti( struct Stream::MultiTarget *targets, int tCount) {
 
     for (struct MultiTarget *t = targets; t < targets+tCount; ++t) {
       // the simple case is if we match, deal with that first.
-      if (c == t->str[t->index]) {
+      if ((char)c == t->str[t->index]) {
         if (++t->index == t->len)
           return t - targets;
         else
@@ -286,7 +286,7 @@ int Stream::findMulti( struct Stream::MultiTarget *targets, int tCount) {
       do {
         --t->index;
         // first check if current char works against the new current index
-        if (c != t->str[t->index])
+        if ((char)c != t->str[t->index])
           continue;
 
         // if it's the only char then we're good, nothing more to check