diff --git a/src/Adafruit_GPS.cpp b/src/Adafruit_GPS.cpp
index 65e5c10..2d8f25a 100644
--- a/src/Adafruit_GPS.cpp
+++ b/src/Adafruit_GPS.cpp
@@ -349,7 +349,13 @@ size_t Adafruit_GPS::write(uint8_t c) {
 
 /**************************************************************************/
 /*!
-    @brief Read one character from the GPS device
+    @brief Read one character from the GPS device.
+
+    Call very frequently and multiple times per opportunity or the buffer
+    may overflow if there are frequent NMEA sentences. An 82 character NMEA
+    sentence 10 times per second will require 820 calls per second, and
+    once a loop() may not be enough. Check for newNMEAreceived() after at
+    least every 10 calls, or you may miss some short sentences.
     @return The character that we received, or 0 if nothing was available
 */
 /**************************************************************************/
@@ -379,8 +385,8 @@ char Adafruit_GPS::read(void) {
       _buff_idx++;
     } else {
       // refill the buffer!
-      if (gpsI2C->requestFrom(0x10, GPS_MAX_I2C_TRANSFER, true) ==
-          GPS_MAX_I2C_TRANSFER) {
+      if (gpsI2C->requestFrom((uint8_t)0x10, (uint8_t)GPS_MAX_I2C_TRANSFER,
+                              (uint8_t) true) == GPS_MAX_I2C_TRANSFER) {
         // got data!
         _buff_max = 0;
         char curr_char = 0;
diff --git a/src/Adafruit_GPS.h b/src/Adafruit_GPS.h
index fe9baee..bf190b4 100644
--- a/src/Adafruit_GPS.h
+++ b/src/Adafruit_GPS.h
@@ -121,7 +121,7 @@ public:
   // NMEA_build.cpp
 #ifdef NMEA_EXTENSIONS
   char *build(char *nmea, const char *thisSource, const char *thisSentence,
-              char ref = 'R');
+              char ref = 'R', bool noCRLF = false);
 #endif
   void addChecksum(char *buff);
 
@@ -170,11 +170,12 @@ public:
                           ///< as received from the GPS (DDDMM.MMMM)
 
   /** Fixed point latitude and longitude value with degrees stored in units of
-    1/100000 degrees, and minutes stored in units of 1/100000 degrees.  See pull
-    #13 for more details:
+    1/10000000 of a degree. See pull #13 for more details:
     https://github.com/adafruit/Adafruit-GPS-Library/pull/13 */
-  int32_t latitude_fixed;  ///< Fixed point latitude in decimal degrees
+  int32_t latitude_fixed;  ///< Fixed point latitude in decimal degrees.
+                           ///< Divide by 10000000.0 to get a double.
   int32_t longitude_fixed; ///< Fixed point longitude in decimal degrees
+                           ///< Divide by 10000000.0 to get a double.
 
   nmea_float_t latitudeDegrees;  ///< Latitude in decimal degrees
   nmea_float_t longitudeDegrees; ///< Longitude in decimal degrees
diff --git a/src/NMEA_build.cpp b/src/NMEA_build.cpp
index 8b78139..a45dad4 100644
--- a/src/NMEA_build.cpp
+++ b/src/NMEA_build.cpp
@@ -71,7 +71,7 @@
 */
 /**************************************************************************/
 char *Adafruit_GPS::build(char *nmea, const char *thisSource,
-                          const char *thisSentence, char ref) {
+                          const char *thisSentence, char ref, bool noCRLF) {
   sprintf(nmea, "%6.2f",
           (double)123.45); // fail if sprintf() doesn't handle floats
   if (strcmp(nmea, "123.45"))
@@ -569,9 +569,10 @@ char *Adafruit_GPS::build(char *nmea, const char *thisSource,
   }
 
   addChecksum(nmea); // Successful completion
-  sprintf(nmea, "%s\r\n",
-          nmea); // Add Carriage Return and Line Feed to comply with NMEA-183
-  return nmea;   // return pointer to finished product
+  if (!noCRLF) { // Add Carriage Return and Line Feed to comply with NMEA-183
+    sprintf(nmea, "%s\r\n", nmea);
+  }
+  return nmea; // return pointer to finished product
 }
 
 #endif // NMEA_EXTENSIONS
diff --git a/src/NMEA_data.cpp b/src/NMEA_data.cpp
index d3d05ed..72a44ef 100644
--- a/src/NMEA_data.cpp
+++ b/src/NMEA_data.cpp
@@ -367,7 +367,11 @@ void Adafruit_GPS::initDataValue(nmea_index_t idx, char *label, char *fmt,
 /*!
     @brief Attempt to add history to a data value table entry. If it fails
     to malloc the space, history will not be added. Test the pointer for a
-    check if needed.
+    check if needed. Select scale and offset values carefully so that
+    operations and results will fit inside 16 bit integer limits. For example
+    a scale of 1.0 and an offset of 100000.0 would be a good choice for
+    atmospheric pressure in Pa with values ranging ~ +/- 3500, while a scale
+    of 10.0 would be pushing the integer limits.
     @param idx The data index for the value to have history recorded
     @param scale Value for scaling the integer history list
     @param offset Value for scaling the integer history list
diff --git a/src/NMEA_parse.cpp b/src/NMEA_parse.cpp
index 822fc57..63be746 100644
--- a/src/NMEA_parse.cpp
+++ b/src/NMEA_parse.cpp
@@ -319,6 +319,21 @@ bool Adafruit_GPS::parse(char *nmea) {
 
   } else if (!strcmp(thisSentence, "RMB")) { //*****************************RMB
     // from Actisense NGW-1 from SH CP150C
+    // RMB Recommended Minimum Navigation Information
+    //       1 2   3 4    5    6       7 8        9 10  11 12  13 14
+    //       | |   | |    |    |       | |        | |   |   |   | |
+    //$--RMB,A,x.x,a,c--c,c--c,llll.ll,a,yyyyy.yy,a,x.x,x.x,x.x,A*hh
+    // 1) Status, V = Navigation receiver warning
+    // 2) Cross Track error - nautical miles
+    // 3) Direction to Steer, Left or Right
+    // 4) TO Waypoint ID
+    // 5) FROM Waypoint ID
+    // 6) Destination Waypoint Latitude 7) N or S
+    // 8) Destination Waypoint Longitude 9) E or W
+    // 10) Range to destination in nautical miles
+    // 11) Bearing to destination in degrees True
+    // 12) Destination closing velocity in knots
+    // 13) Arrival Status, A = Arrival Circle Entered 14) Checksum
     p = strchr(p, ',') + 1; // skip status
     nmea_float_t xte = 100000.;
     char xteDir = 'X';
@@ -339,15 +354,14 @@ bool Adafruit_GPS::parse(char *nmea) {
     if (!isEmpty(p))
       parseStr(fromID, p, NMEA_MAX_WP_ID);
     p = strchr(p, ',') + 1;
-    nmea_float_t latitudeWP =
-        0; // All the same position data for the next way point
+    nmea_float_t latitudeWP = 0;
     nmea_float_t longitudeWP = 0;
     int32_t latitude_fixedWP = 0;
     int32_t longitude_fixedWP = 0;
     nmea_float_t latitudeDegreesWP = 0;
     nmea_float_t longitudeDegreesWP = 0;
-    char latWP = 'N';
-    char lonWP = 'W';
+    char latWP = 'X';
+    char lonWP = 'X';
 
     // parse out both latitude and direction for WayPoint, then go to next
     // field, or fail
@@ -371,8 +385,6 @@ bool Adafruit_GPS::parse(char *nmea) {
     }
     p = strchr(p, ',') + 1;
     p = strchr(p, ',') + 1;
-    p = strchr(p, ',') + 1;
-    p = strchr(p, ',') + 1;
     if (!isEmpty(p))
       newDataValue(NMEA_DISTWP, atof(p));
     p = strchr(p, ',') + 1;
@@ -545,6 +557,7 @@ bool Adafruit_GPS::parse(char *nmea) {
 /**************************************************************************/
 boolean Adafruit_GPS::check(char *nmea) {
   thisCheck = 0; // new check
+  *thisSentence = *thisSource = 0;
   if (*nmea != '$' && *nmea != '!')
     return false; // doesn't start with $ or !
   else
@@ -588,7 +601,10 @@ boolean Adafruit_GPS::check(char *nmea) {
     if (snc) {
       strcpy(thisSentence, snc);
       thisCheck += NMEA_HAS_SENTENCE;
-      return false;
+      return false; // known but not parsed
+    } else {
+      parseStr(thisSentence, p, NMEA_MAX_SENTENCE_ID);
+      return false; // unknown
     }
   }
   return true; // passed all the tests
@@ -764,8 +780,12 @@ bool Adafruit_GPS::parseTime(char *p) {
     hour = time / 10000;
     minute = (time % 10000) / 100;
     seconds = (time % 100);
-    p = strchr(p, '.');
-    milliseconds = atof(p) * 1000;
+    char *dec = strchr(p, '.');
+    char *comstar = min(strchr(p, ','), strchr(p, '*'));
+    if (dec != NULL && comstar != NULL && dec < comstar)
+      milliseconds = atof(p) * 1000;
+    else
+      milliseconds = 0;
     lastTime = sentTime;
     return true;
   }