diff --git a/README.md b/README.md
index 605147d..e534817 100644
--- a/README.md
+++ b/README.md
@@ -472,7 +472,7 @@ As of April 2017, only GoPro HERO5 cameras have a GPMF track. HERO4 Black will h
 | --- | --- | --- | --- | --- |
 | ACCL | 3-axis accelerometer | 200 | m/s² | All HERO5 cameras |
 | GYRO | 3-axis gyroscope | 400 | rad/s | All HERO5 cameras |
-| GPS5 | latitude, longitude, altitude, 2D ground speed, and 3D speed | 18 | deg, deg, m, m/s, m/s | HERO5 Black with GPS enabled |  
+| GPS5 | latitude, longitude, altitude (WGS 84), 2D ground speed, and 3D speed | 18 | deg, deg, m, m/s, m/s | HERO5 Black with GPS enabled |  
 | GPSU | UTC time and data from GPS | 1 | n/a | Within the GPS stream |  
 | GPSF | GPS Fix | 1 | n/a | Within the GPS stream: 0 - no lock, 2 or 3 - 2D or 3D Lock |  
 | GPSP | GPS Precision - Dilution of Precision (DOP x100) | 1 | n/a | Within the GPS stream, under 500 is good |  
diff --git a/demo/GPMF_mp4reader.c b/demo/GPMF_mp4reader.c
index acef3a4..c1d52b7 100644
--- a/demo/GPMF_mp4reader.c
+++ b/demo/GPMF_mp4reader.c
@@ -135,7 +135,8 @@ float OpenGPMFSource(char *filename)  //RAW or within MP4
 	
 	if (fp)
 	{
-		uint32_t tag, qttag, qtsize32, len, skip, type = 0, subtype = 0, num;
+		uint32_t tag, qttag, qtsize32, skip, type = 0, subtype = 0, num;
+		size_t len;
 		int32_t nest = 0;
 		uint64_t nestsize[64] = { 0 };
 		uint64_t lastsize = 0, qtsize;
diff --git a/docs/README.md b/docs/README.md
index 8219e5c..2661973 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -472,7 +472,7 @@ As of April 2017, only GoPro HERO5 cameras have a GPMF track. HERO4 Black will h
 | --- | --- | --- | --- | --- |
 | ACCL | 3-axis accelerometer | 200 | m/s² | All HERO5 cameras |
 | GYRO | 3-axis gyroscope | 400 | rad/s | All HERO5 cameras |
-| GPS5 | latitude, longitude, altitude, 2D ground speed, and 3D speed | 18 | deg, deg, m, m/s, m/s | HERO5 Black with GPS enabled |  
+| GPS5 | latitude, longitude, altitude (WGS 84), 2D ground speed, and 3D speed | 18 | deg, deg, m, m/s, m/s | HERO5 Black with GPS enabled |  
 | GPSU | UTC time and data from GPS | 1 | n/a | Within the GPS stream |  
 | GPSF | GPS Fix | 1 | n/a | Within the GPS stream: 0 - no lock, 2 or 3 - 2D or 3D Lock |  
 | GPSP | GPS Precision - Dilution of Precision (DOP x100) | 1 | n/a | Within the GPS stream, under 500 is good |