diff --git a/src/NMEA_data.cpp b/src/NMEA_data.cpp
index 008e9d2..1b69201 100644
--- a/src/NMEA_data.cpp
+++ b/src/NMEA_data.cpp
@@ -54,15 +54,15 @@ void Adafruit_GPS::newDataValue(nmea_index_t idx, nmea_float_t v) {
 
   // update the smoothed verion
   if (isCompoundAngle(idx)) { // angle with sin/cos component recording
-    newDataValue((nmea_index_t)(idx + 1), sin(v / RAD_TO_DEG));
-    newDataValue((nmea_index_t)(idx + 2), cos(v / RAD_TO_DEG));
+    newDataValue((nmea_index_t)(idx + 1), sin(v / (nmea_float_t)RAD_TO_DEG));
+    newDataValue((nmea_index_t)(idx + 2), cos(v / (nmea_float_t)RAD_TO_DEG));
   }
   // weighting factor for smoothing depends on delta t / tau
   nmea_float_t w =
       min((nmea_float_t)1.0,
           (nmea_float_t)(millis() - val[idx].lastUpdate) / val[idx].response);
   // default smoothing
-  val[idx].smoothed = (1.0 - w) * val[idx].smoothed + w * v;
+  val[idx].smoothed = (1.0f - w) * val[idx].smoothed + w * v;
   // special smoothing for some angle types
   if (val[idx].type == NMEA_COMPASS_ANGLE_SIN)
     val[idx].smoothed =
@@ -403,7 +403,7 @@ nmea_history_t *Adafruit_GPS::initHistory(nmea_index_t idx, nmea_float_t scale,
     }
     if (val[idx].hist != NULL) {
       val[idx].hist->n = historyN;
-      if (scale > 0.0)
+      if (scale > 0.0f)
         val[idx].hist->scale = scale;
       val[idx].hist->offset = offset;
       if (historyInterval > 0)
@@ -517,18 +517,18 @@ bool Adafruit_GPS::isCompoundAngle(nmea_index_t idx) {
 */
 /**************************************************************************/
 nmea_float_t Adafruit_GPS::boatAngle(nmea_float_t s, nmea_float_t c) {
-  nmea_float_t sAng =
-      asin(s) * RAD_TO_DEG; // put the sin angle in -90 to 90 range
+  // put the sin angle in -90 to 90 range
+  nmea_float_t sAng = asin(s) * (nmea_float_t)RAD_TO_DEG;
   while (sAng < -90)
-    sAng += 180.;
+    sAng += 180.0f;
   while (sAng > 90)
-    sAng -= 180.;
-  nmea_float_t cAng =
-      acos(c) * RAD_TO_DEG; // put the cos angle in 0 to 180 range
+    sAng -= 180.0f;
+  // put the cos angle in 0 to 180 range
+  nmea_float_t cAng = acos(c) * (nmea_float_t)RAD_TO_DEG;
   while (cAng < 0)
-    cAng += 180.;
+    cAng += 180.0f;
   while (cAng > 180)
-    cAng -= 180.;
+    cAng -= 180.0f;
   // Pick the most accurate representation and translate
   if (cAng < 45)
     return sAng; //            Close hauled
@@ -561,9 +561,9 @@ nmea_float_t Adafruit_GPS::compassAngle(nmea_float_t s, nmea_float_t c) {
   nmea_float_t ang = boatAngle(s, c);
   if (ang < 5000) { // if reasonable range
     while (ang < 0)
-      ang += 360.; // round up
+      ang += 360.0f; // round up
     while (ang > 360)
-      ang -= 360.; // round down
+      ang -= 360.0f; // round down
   }
   return ang;
 }
diff --git a/src/NMEA_parse.cpp b/src/NMEA_parse.cpp
index 63be746..7e9e71e 100644
--- a/src/NMEA_parse.cpp
+++ b/src/NMEA_parse.cpp
@@ -184,15 +184,17 @@ bool Adafruit_GPS::parse(char *nmea) {
     // feet, metres, fathoms below transducer coerced to water depth from
     // surface in metres
     if (!isEmpty(p))
-      newDataValue(NMEA_DEPTH, atof(p) * 0.3048 + depthToTransducer);
+      newDataValue(NMEA_DEPTH,
+                   (nmea_float_t)atof(p) * 0.3048f + depthToTransducer);
     p = strchr(p, ',') + 1;
     p = strchr(p, ',') + 1;
     if (!isEmpty(p))
-      newDataValue(NMEA_DEPTH, atof(p) + depthToTransducer);
+      newDataValue(NMEA_DEPTH, (nmea_float_t)atof(p) + depthToTransducer);
     p = strchr(p, ',') + 1;
     p = strchr(p, ',') + 1;
     if (!isEmpty(p))
-      newDataValue(NMEA_DEPTH, atof(p) * 6 * 0.3048 + depthToTransducer);
+      newDataValue(NMEA_DEPTH,
+                   (nmea_float_t)atof(p) * 6 * 0.3048f + depthToTransducer);
 
   } else if (!strcmp(thisSentence, "DPT")) { //*****************************DPT
     // from Actisense NGW-1
@@ -233,7 +235,7 @@ bool Adafruit_GPS::parse(char *nmea) {
       u = *p;
     p = strchr(p, ',') + 1;
     if (u != 'C') {
-      T = (T - 32) / 1.8;
+      T = (T - 32) / 1.8f;
       u = 'C';
     } // coerce to C
     if (T < 1000)
@@ -247,7 +249,7 @@ bool Adafruit_GPS::parse(char *nmea) {
       u = *p;
     p = strchr(p, ',') + 1;
     if (u != 'C') {
-      T = (T - 32) / 1.8;
+      T = (T - 32) / 1.8f;
       u = 'C';
     }
     if (T < 1000)
@@ -264,7 +266,7 @@ bool Adafruit_GPS::parse(char *nmea) {
     if (!isEmpty(p))
       u = *p; // last before checksum
     if (u != 'C') {
-      T = (T - 32) / 1.8;
+      T = (T - 32) / 1.8f;
       u = 'C';
     }
     if (T < 1000)
@@ -296,24 +298,24 @@ bool Adafruit_GPS::parse(char *nmea) {
     if (!isEmpty(p))
       stat = *p; // last before checksum
     if (units == 'K') {
-      spd /= 1.6;
+      spd /= 1.6f;
       units = 'M';
     }
     if (units == 'M') {
-      spd *= 5280. / 6000.;
+      spd *= 5280.0f / 6000.0f;
       units = 'N';
     }
-    if (ang > 180.)
-      ang -= 360.;
+    if (ang > 180.0f)
+      ang -= 360.0f;
     if (ref == 'R') {
-      if (ang < 1000. && stat == 'A')
+      if (ang < 1000.0f && stat == 'A')
         newDataValue(NMEA_AWA, ang);
-      if (spd < 1000. && stat == 'A')
+      if (spd < 1000.0f && stat == 'A')
         newDataValue(NMEA_AWS, spd);
     } else {
-      if (ang < 1000. && stat == 'A')
+      if (ang < 1000.0f && stat == 'A')
         newDataValue(NMEA_TWA, ang);
-      if (spd < 1000. && stat == 'A')
+      if (spd < 1000.0f && stat == 'A')
         newDataValue(NMEA_TWS, spd);
     }
 
@@ -343,9 +345,9 @@ bool Adafruit_GPS::parse(char *nmea) {
     if (!isEmpty(p))
       xteDir = *p;
     p = strchr(p, ',') + 1;
-    if (xte < 10000. && xteDir != 'X') {
+    if (xte < 10000.0f && xteDir != 'X') {
       if (xteDir == 'L')
-        xte *= -1.;
+        xte *= -1.0f;
       newDataValue(NMEA_XTE, xte);
     }
     if (!isEmpty(p))
@@ -452,7 +454,7 @@ bool Adafruit_GPS::parse(char *nmea) {
     p = strchr(p, ',') + 1;
     if (!isEmpty(p))
       vmg = atof(p) * 0.3048 * 3600. / 6000.; // skip units
-    if (vmg < 1000.)
+    if (vmg < 1000.0f)
       newDataValue(NMEA_VMG, vmg);
   } else if (!strcmp(thisSentence, "VTG")) { //*****************************VTG
     // from Actisense NGW-1 from SH CP150C
@@ -470,7 +472,7 @@ bool Adafruit_GPS::parse(char *nmea) {
     p = strchr(p, ',') + 1;
     if (ref == 'L')
       ang *= -1;
-    if (ang < 1000.)
+    if (ang < 1000.0f)
       newDataValue(NMEA_AWA, ang);
     nmea_float_t ws = 0.0;
     char units = 'X';
@@ -492,15 +494,15 @@ bool Adafruit_GPS::parse(char *nmea) {
     if (!isEmpty(p))
       units = *p; // last before checksum
     if (units == 'M') {
-      ws *= 3.6;
+      ws *= 3.6f;
       units = 'K';
     } // convert m/s to km/h
     if (units == 'K') {
-      ws /= 1.6;
+      ws /= 1.6f;
       units = 'M';
     } // convert km/h to miles / h
     if (units == 'M') {
-      ws *= 5280. / 6000.;
+      ws *= 5280.0f / 6000.0f;
       units = 'N';
     } // convert miles / hr to knots
     if (units == 'N')
@@ -523,9 +525,9 @@ bool Adafruit_GPS::parse(char *nmea) {
     if (!isEmpty(p))
       xteDir = *p;
     p = strchr(p, ',') + 1;
-    if (xte < 10000. && xteDir != 'X') {
+    if (xte < 10000.0f && xteDir != 'X') {
       if (xteDir == 'L')
-        xte *= -1.;
+        xte *= -1.0f;
       newDataValue(NMEA_XTE, xte);
     } // skip units
 
@@ -555,7 +557,7 @@ bool Adafruit_GPS::parse(char *nmea) {
     @return True if well formed, false if it has problems
 */
 /**************************************************************************/
-boolean Adafruit_GPS::check(char *nmea) {
+bool Adafruit_GPS::check(char *nmea) {
   thisCheck = 0; // new check
   *thisSentence = *thisSource = 0;
   if (*nmea != '$' && *nmea != '!')
@@ -799,7 +801,7 @@ bool Adafruit_GPS::parseTime(char *p) {
     @return True if we parsed it, false if it has invalid data
 */
 /**************************************************************************/
-boolean Adafruit_GPS::parseFix(char *p) {
+bool Adafruit_GPS::parseFix(char *p) {
   if (!isEmpty(p)) {
     if (p[0] == 'A') {
       fix = true;