diff --git a/doc/stages/filters.ferry.rst b/doc/stages/filters.ferry.rst
index 1dc03efb06..00244bb1b8 100644
--- a/doc/stages/filters.ferry.rst
+++ b/doc/stages/filters.ferry.rst
@@ -7,11 +7,11 @@ The ferry filter copies data from one dimension to another, creates new
 dimensions or both.
 
 The filter is guided by a list of 'from' and 'to' dimensions in the format
-<from>=<to>.  Data from the 'from' dimension is copied to the 'to' dimension.
+<from>=><to>.  Data from the 'from' dimension is copied to the 'to' dimension.
 The 'from' dimension must exist.  The 'to' dimension can be pre-existing or
 will be created by the ferry filter.
 
-Alternatively, the format =<to> can be used to create a new dimension without
+Alternatively, the format =><to> can be used to create a new dimension without
 copying data from any source.  The values of the 'to' dimension are default
 initialized.
 
@@ -40,7 +40,7 @@ pre-reprojection values and the post-reprojection values.
         },
         {
           "type":"filters.ferry",
-          "dimensions":"X = StatePlaneX, Y=StatePlaneY"
+          "dimensions":"X => StatePlaneX, Y=>StatePlaneY"
         },
         {
           "type":"filters.reprojection",
@@ -71,7 +71,7 @@ so that the value can be set to '2' and written as a LAS file.
         },
         {
             "type": "filters.ferry",
-            "dimensions": "=Classification"
+            "dimensions": "=>Classification"
         },
         {
             "type": "filters.assign",
@@ -86,6 +86,10 @@ Options
 
 dimensions
   A list of dimensions whose values should be copied.
-  The format of the option is <from>=<to>, <from>=<to>,... Spaces are ignored.
+  The format of the option is <from>=><to>, <from>=><to>,...
+  Spaces are ignored.
   'from' can be left empty, in which case the 'to' dimension is created and
   default-initialized.  'to' dimensions will be created if necessary.
+
+  Note: the old syntax that used '=' instead of '=>' between dimension names
+  is still supported.
diff --git a/filters/FerryFilter.cpp b/filters/FerryFilter.cpp
index 954f8975e3..6661883c86 100644
--- a/filters/FerryFilter.cpp
+++ b/filters/FerryFilter.cpp
@@ -64,8 +64,12 @@ void FerryFilter::initialize()
         StringList s = Utils::split(dim, '=');
         if (s.size() != 2)
             throwError("Invalid dimension specified '" + dim + "'.  Need "
-                "<from dimension>=<to dimension>.  See documentation for "
+                "<from dimension>=><to dimension>.  See documentation for "
                 "details.");
+        // Allow new '=>' syntax
+        if (s[1][0] == '>')
+            s[1].erase(s[1].begin());
+
         Utils::trim(s[0]);
         Utils::trim(s[1]);
         if (s[0] == s[1])
diff --git a/io/GDALWriter.cpp b/io/GDALWriter.cpp
index 9c3223db04..65d9f86531 100644
--- a/io/GDALWriter.cpp
+++ b/io/GDALWriter.cpp
@@ -210,6 +210,10 @@ bool GDALWriter::processOne(PointRef& point)
 
 void GDALWriter::doneFile()
 {
+    if (!m_grid) {
+        throw pdal_error("Unable to write GDAL data, grid is uninitialized. You "
+                "might have provided the GDALWriter zero points.");
+    }
     std::array<double, 6> pixelToPos;
 
     pixelToPos[0] = m_curBounds.minx;
diff --git a/scripts/ci/script.sh b/scripts/ci/script.sh
index 8082231c66..0f53fb8eb7 100755
--- a/scripts/ci/script.sh
+++ b/scripts/ci/script.sh
@@ -2,11 +2,12 @@
 # Builds and tests PDAL
 
 echo "http://dl-cdn.alpinelinux.org/alpine/edge/testing" >> /etc/apk/repositories
+echo "@edgecommunity http://dl-cdn.alpinelinux.org/alpine/edge/community" >> /etc/apk/repositories; \
 apk update
 apk add \
     cmake \
     alpine-sdk \
-    eigen-dev \
+    eigen-dev@edgecommunity \
     hexer \
     hexer-dev \
     nitro \
diff --git a/scripts/docker/Dockerfile b/scripts/docker/Dockerfile
index 928bafb8b5..bcef8e97ec 100644
--- a/scripts/docker/Dockerfile
+++ b/scripts/docker/Dockerfile
@@ -2,12 +2,13 @@ FROM alpine:3.7
 
 RUN \
     echo "http://dl-cdn.alpinelinux.org/alpine/edge/testing" >> /etc/apk/repositories; \
+    echo "@edgecommunity http://dl-cdn.alpinelinux.org/alpine/edge/community" >> /etc/apk/repositories; \
     apk update; \
     apk add --no-cache --virtual .build-deps \
         alpine-sdk \
         unzip \
         cmake \
-        eigen-dev \
+        eigen-dev@edgecommunity \
         hexer-dev \
         nitro-dev \
         gdal-dev \
diff --git a/test/unit/filters/FerryFilterTest.cpp b/test/unit/filters/FerryFilterTest.cpp
index 67d77bd04d..49dc0ac2e3 100644
--- a/test/unit/filters/FerryFilterTest.cpp
+++ b/test/unit/filters/FerryFilterTest.cpp
@@ -65,7 +65,7 @@ TEST(FerryFilterTest, stream)
     r.setOptions(ro);
 
     Options fo;
-    fo.add("dimensions", "X=FooX,Y=BarY");
+    fo.add("dimensions", "X=FooX,Y=>BarY");
 
     FerryFilter f;
     f.setOptions(fo);
@@ -167,7 +167,7 @@ TEST(FerryFilterTest, test_ferry_invalid)
 
     Options op4;
 
-    op4.add("dimensions", "X = Y, X = NewZ = NewQ");
+    op4.add("dimensions", "X = Y, X => NewZ = NewQ");
     FerryFilter f4;
     f4.setInput(reader);
     f4.setOptions(op4);
diff --git a/test/unit/io/GDALWriterTest.cpp b/test/unit/io/GDALWriterTest.cpp
index 86bd251812..579f85b963 100644
--- a/test/unit/io/GDALWriterTest.cpp
+++ b/test/unit/io/GDALWriterTest.cpp
@@ -35,6 +35,7 @@
 #include <pdal/pdal_test_main.hpp>
 #include <pdal/GDALUtils.hpp>
 #include <pdal/util/FileUtils.hpp>
+#include <filters/RangeFilter.hpp>
 #include <io/GDALWriter.hpp>
 #include <io/LasReader.hpp>
 #include <io/TextReader.hpp>
@@ -546,3 +547,31 @@ TEST(GDALWriterTest, btint)
         EXPECT_NEAR(arr[i], data[i], .001);
 }
 
+TEST(GDALWriterTest, no_points)
+{
+    std::string outfile(Support::temppath("out.tif"));
+    FileUtils::deleteFile(outfile);
+
+    LasReader r;
+    Options ro;
+    ro.add("filename", Support::datapath("las/no-points.las"));
+    r.setOptions(ro);
+
+    RangeFilter f;
+    f.setInput(r);
+    Options fo;
+    fo.add("limits", "Classification[2:2]");
+    f.setOptions(fo);
+
+    GDALWriter w;
+    w.setInput(f);
+    Options wo;
+    wo.add("resolution", 2);
+    wo.add("filename", outfile);
+    w.setOptions(wo);
+
+    PointTable t;
+    w.prepare(t);
+    EXPECT_THROW(w.execute(t), pdal_error);
+}
+