diff --git a/minmea.c b/minmea.c
index bd6fb06..fb3260b 100644
--- a/minmea.c
+++ b/minmea.c
@@ -19,9 +19,9 @@ static int hex2int(char c)
     if (c >= '0' && c <= '9')
         return c - '0';
     if (c >= 'A' && c <= 'F')
-        return c - 'A';
+        return c - 'A' + 10;
     if (c >= 'a' && c <= 'f')
-        return c - 'a';
+        return c - 'a' + 10;
     return -1;
 }
 
diff --git a/tests.c b/tests.c
index 1744a3c..f29d1dc 100644
--- a/tests.c
+++ b/tests.c
@@ -20,6 +20,8 @@ static const char *valid_sequences[] = {
     "$GPGGA,,,,,,0,00,99.99,,,,,,*48",
     "$GPGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*30",
     "$GPGLL,,,,,,V,N*64",
+    "$GPXTE,A,A,0.67,L,N*6F",
+    "$GPXTE,A,A,0.67,L,N*6f",
     NULL,
 };
 
@@ -32,6 +34,8 @@ static const char *invalid_sequences[] = {
     "$$GPGGA,,,,,,0,00,99.99,,,,,,*48",
     "GPGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*30",
     "gps: $GPGLL,,,,,,V,N",
+    "$GPXTE,A,A,0.67,L,N*6e",
+    "$GPXTE,A,A,0.67,L,N*6g",
     NULL,
 };