diff --git a/Lib/fontTools/varLib/__init__.py b/Lib/fontTools/varLib/__init__.py
index cde090330..6bbd6b608 100644
--- a/Lib/fontTools/varLib/__init__.py
+++ b/Lib/fontTools/varLib/__init__.py
@@ -513,7 +513,11 @@ def _merge_OTL(font, model, master_fonts, axisTags):
 	merger = VariationMerger(model, axisTags, font)
 
 	merger.mergeTables(font, master_fonts, ['GPOS'])
+	# TODO Merge GSUB
+	# TODO Merge GDEF itself!
 	store = merger.store_builder.finish()
+	if not store.VarData:
+		return
 	try:
 		GDEF = font['GDEF'].table
 		assert GDEF.Version <= 0x00010002
@@ -527,7 +531,8 @@ def _merge_OTL(font, model, master_fonts, axisTags):
 	# Optimize
 	varidx_map = store.optimize()
 	GDEF.remap_device_varidxes(varidx_map)
-	font['GPOS'].table.remap_device_varidxes(varidx_map)
+	if 'GPOS' in font:
+		font['GPOS'].table.remap_device_varidxes(varidx_map)
 
 
 
diff --git a/Lib/fontTools/varLib/varStore.py b/Lib/fontTools/varLib/varStore.py
index 5a642a9cf..b26298763 100644
--- a/Lib/fontTools/varLib/varStore.py
+++ b/Lib/fontTools/varLib/varStore.py
@@ -22,14 +22,24 @@ class OnlineVarStoreBuilder(object):
 		self._regionMap = {}
 		self._regionList = buildVarRegionList([], axisTags)
 		self._store = buildVarStore(self._regionList, [])
+		self._data = None
 
 	def setModel(self, model):
 		self._model = model
 
+	def finish(self, optimize=True):
+		self._regionList.RegionCount = len(self._regionList.Region)
+		self._store.VarDataCount = len(self._store.VarData)
+		for data in self._store.VarData:
+			data.ItemCount = len(data.Item)
+			VarData_CalculateNumShorts(data, optimize)
+		return self._store
+
+	def _add_VarData(self):
 		regionMap = self._regionMap
 		regionList = self._regionList
 
-		regions = model.supports[1:]
+		regions = self._model.supports[1:]
 		regionIndices = []
 		for region in regions:
 			key = _getLocationKey(region)
@@ -44,21 +54,15 @@ class OnlineVarStoreBuilder(object):
 		self._outer = len(self._store.VarData)
 		self._store.VarData.append(data)
 
-	def finish(self, optimize=True):
-		self._regionList.RegionCount = len(self._regionList.Region)
-		self._store.VarDataCount = len(self._store.VarData)
-		for data in self._store.VarData:
-			data.ItemCount = len(data.Item)
-			VarData_CalculateNumShorts(data, optimize)
-		return self._store
-
 	def storeMasters(self, master_values):
+		if not self._data:
+			self._add_VarData()
 		deltas = [round(d) for d in self._model.getDeltas(master_values)]
 		base = deltas.pop(0)
 		inner = len(self._data.Item)
 		if inner == 0xFFFF:
 			# Full array. Start new one.
-			self.setModel(self._model)
+			self._add_VarData()
 			return self.storeMasters(master_values)
 		self._data.Item.append(deltas)
 		return base, (self._outer << 16) + inner
diff --git a/Tests/varLib/data/test_results/Build.ttx b/Tests/varLib/data/test_results/Build.ttx
index 9f43e7731..5d665e35f 100644
--- a/Tests/varLib/data/test_results/Build.ttx
+++ b/Tests/varLib/data/test_results/Build.ttx
@@ -1,83 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <ttFont sfntVersion="\x00\x01\x00\x00" ttLibVersion="3.17">
 
-  <GDEF>
-    <Version value="0x00010003"/>
-    <VarStore Format="1">
-      <Format value="1"/>
-      <VarRegionList>
-        <!-- RegionAxisCount=2 -->
-        <!-- RegionCount=5 -->
-        <Region index="0">
-          <VarRegionAxis index="0">
-            <StartCoord value="-1.0"/>
-            <PeakCoord value="-1.0"/>
-            <EndCoord value="0.0"/>
-          </VarRegionAxis>
-          <VarRegionAxis index="1">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="0.0"/>
-            <EndCoord value="0.0"/>
-          </VarRegionAxis>
-        </Region>
-        <Region index="1">
-          <VarRegionAxis index="0">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="1.0"/>
-            <EndCoord value="1.0"/>
-          </VarRegionAxis>
-          <VarRegionAxis index="1">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="0.0"/>
-            <EndCoord value="0.0"/>
-          </VarRegionAxis>
-        </Region>
-        <Region index="2">
-          <VarRegionAxis index="0">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="0.0"/>
-            <EndCoord value="0.0"/>
-          </VarRegionAxis>
-          <VarRegionAxis index="1">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="1.0"/>
-            <EndCoord value="1.0"/>
-          </VarRegionAxis>
-        </Region>
-        <Region index="3">
-          <VarRegionAxis index="0">
-            <StartCoord value="-1.0"/>
-            <PeakCoord value="-1.0"/>
-            <EndCoord value="0.0"/>
-          </VarRegionAxis>
-          <VarRegionAxis index="1">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="1.0"/>
-            <EndCoord value="1.0"/>
-          </VarRegionAxis>
-        </Region>
-        <Region index="4">
-          <VarRegionAxis index="0">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="1.0"/>
-            <EndCoord value="1.0"/>
-          </VarRegionAxis>
-          <VarRegionAxis index="1">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="1.0"/>
-            <EndCoord value="1.0"/>
-          </VarRegionAxis>
-        </Region>
-      </VarRegionList>
-      <!-- VarDataCount=1 -->
-      <VarData index="0">
-        <!-- ItemCount=0 -->
-        <NumShorts value="0"/>
-        <!-- VarRegionCount=0 -->
-      </VarData>
-    </VarStore>
-  </GDEF>
-
   <HVAR>
     <Version value="0x00010000"/>
     <VarStore Format="1">
diff --git a/Tests/varLib/data/test_results/Build3.ttx b/Tests/varLib/data/test_results/Build3.ttx
index 656697a00..a6ae23ed8 100644
--- a/Tests/varLib/data/test_results/Build3.ttx
+++ b/Tests/varLib/data/test_results/Build3.ttx
@@ -1,30 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <ttFont sfntVersion="\x00\x01\x00\x00" ttLibVersion="3.14">
 
-  <GDEF>
-    <Version value="0x00010003"/>
-    <VarStore Format="1">
-      <Format value="1"/>
-      <VarRegionList>
-        <!-- RegionAxisCount=1 -->
-        <!-- RegionCount=1 -->
-        <Region index="0">
-          <VarRegionAxis index="0">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="1.0"/>
-            <EndCoord value="1.0"/>
-          </VarRegionAxis>
-        </Region>
-      </VarRegionList>
-      <!-- VarDataCount=1 -->
-      <VarData index="0">
-        <!-- ItemCount=0 -->
-        <NumShorts value="0"/>
-        <!-- VarRegionCount=0 -->
-      </VarData>
-    </VarStore>
-  </GDEF>
-
   <HVAR>
     <Version value="0x00010000"/>
     <VarStore Format="1">
@@ -92,17 +68,17 @@
         <NumShorts value="0"/>
         <!-- VarRegionCount=1 -->
         <VarRegionIndex index="0" value="0"/>
-        <Item index="0" value="[22]"/>
-        <Item index="1" value="[13]"/>
+        <Item index="0" value="[13]"/>
+        <Item index="1" value="[22]"/>
       </VarData>
     </VarStore>
     <ValueRecord index="0">
       <ValueTag value="stro"/>
-      <VarIdx value="1"/>
+      <VarIdx value="0"/>
     </ValueRecord>
     <ValueRecord index="1">
       <ValueTag value="xhgt"/>
-      <VarIdx value="0"/>
+      <VarIdx value="1"/>
     </ValueRecord>
   </MVAR>
 
diff --git a/Tests/varLib/data/test_results/BuildMain.ttx b/Tests/varLib/data/test_results/BuildMain.ttx
index 9a3297304..f30351e5f 100644
--- a/Tests/varLib/data/test_results/BuildMain.ttx
+++ b/Tests/varLib/data/test_results/BuildMain.ttx
@@ -616,83 +616,6 @@
     </extraNames>
   </post>
 
-  <GDEF>
-    <Version value="0x00010003"/>
-    <VarStore Format="1">
-      <Format value="1"/>
-      <VarRegionList>
-        <!-- RegionAxisCount=2 -->
-        <!-- RegionCount=5 -->
-        <Region index="0">
-          <VarRegionAxis index="0">
-            <StartCoord value="-1.0"/>
-            <PeakCoord value="-1.0"/>
-            <EndCoord value="0.0"/>
-          </VarRegionAxis>
-          <VarRegionAxis index="1">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="0.0"/>
-            <EndCoord value="0.0"/>
-          </VarRegionAxis>
-        </Region>
-        <Region index="1">
-          <VarRegionAxis index="0">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="1.0"/>
-            <EndCoord value="1.0"/>
-          </VarRegionAxis>
-          <VarRegionAxis index="1">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="0.0"/>
-            <EndCoord value="0.0"/>
-          </VarRegionAxis>
-        </Region>
-        <Region index="2">
-          <VarRegionAxis index="0">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="0.0"/>
-            <EndCoord value="0.0"/>
-          </VarRegionAxis>
-          <VarRegionAxis index="1">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="1.0"/>
-            <EndCoord value="1.0"/>
-          </VarRegionAxis>
-        </Region>
-        <Region index="3">
-          <VarRegionAxis index="0">
-            <StartCoord value="-1.0"/>
-            <PeakCoord value="-1.0"/>
-            <EndCoord value="0.0"/>
-          </VarRegionAxis>
-          <VarRegionAxis index="1">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="1.0"/>
-            <EndCoord value="1.0"/>
-          </VarRegionAxis>
-        </Region>
-        <Region index="4">
-          <VarRegionAxis index="0">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="1.0"/>
-            <EndCoord value="1.0"/>
-          </VarRegionAxis>
-          <VarRegionAxis index="1">
-            <StartCoord value="0.0"/>
-            <PeakCoord value="1.0"/>
-            <EndCoord value="1.0"/>
-          </VarRegionAxis>
-        </Region>
-      </VarRegionList>
-      <!-- VarDataCount=1 -->
-      <VarData index="0">
-        <!-- ItemCount=0 -->
-        <NumShorts value="0"/>
-        <!-- VarRegionCount=0 -->
-      </VarData>
-    </VarStore>
-  </GDEF>
-
   <HVAR>
     <Version value="0x00010000"/>
     <VarStore Format="1">