diff --git a/bin/download-testfiles.sh b/bin/download-testfiles.sh
index 590f55b..e26d98a 100755
--- a/bin/download-testfiles.sh
+++ b/bin/download-testfiles.sh
@@ -3,7 +3,7 @@ set -ex
 
 mkdir -p tests/testfiles
 
-for file in srtm_38_03 srtm_67_19 srtm_36_02 srtm_40_17 srtm_22_04
+for file in srtm_38_03 srtm_38_02 srtm_67_19 srtm_36_02 srtm_40_17 srtm_22_04
 do
     if [ ! -f tests/testfiles/${file}.tif ]
     then
diff --git a/src/Provider/GeoTIFF/GeoTIFFReader.php b/src/Provider/GeoTIFF/GeoTIFFReader.php
index e0afed7..3839b3e 100644
--- a/src/Provider/GeoTIFF/GeoTIFFReader.php
+++ b/src/Provider/GeoTIFF/GeoTIFFReader.php
@@ -173,6 +173,6 @@ public function getElevationFor($row, $col)
 
         $elevation = unpack('velevation', fread($this->FileResource, static::BYTES_PER_SAMPLE))['elevation'];
 
-        return ($elevation <= self::UNKNOWN || $elevation === -self::UNKNOWN) ? false : $elevation;
+        return ($elevation <= self::UNKNOWN || $elevation >= -self::UNKNOWN) ? false : $elevation;
     }
 }
diff --git a/src/Tests/Provider/GeoTIFF/SRTM4ProviderTest.php b/src/Tests/Provider/GeoTIFF/SRTM4ProviderTest.php
index e178a8e..9572ecb 100644
--- a/src/Tests/Provider/GeoTIFF/SRTM4ProviderTest.php
+++ b/src/Tests/Provider/GeoTIFF/SRTM4ProviderTest.php
@@ -92,7 +92,6 @@ public function testTileBoundary()
         $this->checkFile('srtm_38_03.tif');
 
         if (
-            !$this->fileIsThere('srtm_38_02.tif') &&
             !$this->fileIsThere('srtm_37_02.tif') &&
             !$this->fileIsThere('srtm_37_03.tif') &&
             !$this->fileIsThere('srtm_38_04.tif') &&
@@ -100,7 +99,6 @@ public function testTileBoundary()
             !$this->fileIsThere('srtm_39_04.tif')
         ) {
             $this->assertTrue($this->Provider->hasDataFor([[50.00000, 5.00000]]));
-            $this->assertFalse($this->Provider->hasDataFor([[50.00001, 5.00000]]));
             $this->assertFalse($this->Provider->hasDataFor([[50.00000, 4.99999]]));
 
             $this->assertTrue($this->Provider->hasDataFor([[45.00001, 9.99999]]));
@@ -191,4 +189,17 @@ public function testNewYorkWithoutInterpolation()
             )
         );
     }
+
+    /**
+     * @see https://github.com/Runalyze/dem-reader/issues/1
+     */
+    public function testUnknownValuesSavedAs65535()
+    {
+        $this->checkFile('srtm_38_02.tif');
+
+        $this->assertEquals(
+            [3],
+            $this->Provider->getElevations([54.44702], [9.875502])
+        );
+    }
 }