diff --git a/wa/framework/getters.py b/wa/framework/getters.py
index e2ca572c..e4572070 100644
--- a/wa/framework/getters.py
+++ b/wa/framework/getters.py
@@ -71,6 +71,14 @@ def get_generic_resource(resource, files):
     return matches[0]
 
 
+def get_path_matches(resource, files):
+    matches = []
+    for f in files:
+        if resource.match_path(f):
+            matches.append(f)
+    return  matches
+
+
 def get_from_location(basepath, resource):
     if resource.kind == 'file':
         path = os.path.join(basepath, resource.path)
@@ -204,10 +212,15 @@ class Http(ResourceGetter):
             return  # TODO: add support for unowned resources
         if not self.index:
             self.index = self.fetch_index()
-        asset = self.resolve_resource(resource)
-        if not asset:
-            return
-        return self.download_asset(asset, resource.owner.name)
+        if resource.kind == 'apk':
+            # APKs must always be downloaded to run ApkInfo for version
+            # information.
+            return self.resolve_apk(resource)
+        else:
+            asset = self.resolve_resource(resource)
+            if not asset:
+                return
+            return self.download_asset(asset, resource.owner.name)
 
     def fetch_index(self):
         if not self.url:
@@ -251,6 +264,20 @@ class Http(ResourceGetter):
             auth = None
         return requests.get(url, auth=auth, stream=stream)
 
+    def resolve_apk(self, resource):
+        assets = self.index.get(resource.owner.name, {})
+        if not assets:
+            return None
+        asset_map = {a['path']: a for a in assets}
+        paths = get_path_matches(resource, asset_map.keys())
+        local_paths = []
+        for path in paths:
+            local_paths.append(self.download_asset(asset_map[path],
+                                                   resource.owner.name))
+        for path in local_paths:
+            if resource.match(path):
+                return path
+
     def resolve_resource(self, resource):
         # pylint: disable=too-many-branches,too-many-locals
         assets = self.index.get(resource.owner.name, {})
@@ -258,13 +285,7 @@ class Http(ResourceGetter):
             return {}
 
         asset_map = {a['path']: a for a in assets}
-        if resource.kind in ['apk', 'jar', 'revent']:
-            if resource.kind == 'apk' and resource.version:
-                # TODO: modify the index format to attach version info to the
-                #       APK entries.
-                msg = 'Versions of APKs cannot be fetched over HTTP at this time'
-                self.logger.warning(msg)
-                return {}
+        if resource.kind in ['jar', 'revent']:
             path = get_generic_resource(resource, asset_map.keys())
             if path:
                 return asset_map[path]
diff --git a/wa/framework/resource.py b/wa/framework/resource.py
index ec8d36bc..b137fae9 100644
--- a/wa/framework/resource.py
+++ b/wa/framework/resource.py
@@ -72,6 +72,9 @@ class Resource(object):
         self.owner = owner
 
     def match(self, path):
+        return self.match_path(path)
+
+    def match_path(self, path):
         raise NotImplementedError()
 
     def __str__(self):
@@ -86,7 +89,7 @@ class File(Resource):
         super(File, self).__init__(owner)
         self.path = path
 
-    def match(self, path):
+    def match_path(self, path):
         return self.path == path
 
     def __str__(self):
@@ -102,7 +105,7 @@ class Executable(Resource):
         self.abi = abi
         self.filename = filename
 
-    def match(self, path):
+    def match_path(self, path):
         return self.filename == os.path.basename(path)
 
     def __str__(self):
@@ -118,7 +121,7 @@ class ReventFile(Resource):
         self.stage = stage
         self.target = target
 
-    def match(self, path):
+    def match_path(self, path):
         filename = os.path.basename(path)
         parts = filename.split('.')
         if len(parts) > 2:
@@ -133,7 +136,7 @@ class JarFile(Resource):
 
     kind = 'jar'
 
-    def match(self, path):
+    def match_path(self, path):
         # An owner always  has at most one jar file, so
         # always match
         return True
@@ -154,6 +157,10 @@ class ApkFile(Resource):
         self.exact_abi = exact_abi
         self.supported_abi = supported_abi
 
+    def match_path(self, path):
+        ext = os.path.splitext(path)[1].lower()
+        return ext == '.apk'
+
     def match(self, path):
         name_matches = True
         version_matches = True
diff --git a/wa/instrumentation/energy_measurement.py b/wa/instrumentation/energy_measurement.py
index 95fcad02..d4d77c76 100644
--- a/wa/instrumentation/energy_measurement.py
+++ b/wa/instrumentation/energy_measurement.py
@@ -30,7 +30,7 @@ from wa import Instrument, Parameter
 from wa.framework import pluginloader
 from wa.framework.plugin import Plugin
 from wa.framework.exception import ConfigError, InstrumentError
-from wa.utils.types import list_of_strings, list_of_ints, list_or_string, obj_dict
+from wa.utils.types import list_of_strings, list_of_ints, list_or_string, obj_dict, identifier
 
 
 class EnergyInstrumentBackend(Plugin):
@@ -249,10 +249,15 @@ class EnergyMeasurement(Instrument):
         self.backend = self.loader.get_plugin(self.instrument)
         self.params = obj_dict()
 
+        instrument_parameters = {identifier(k): v
+                                 for k, v in self.instrument_parameters.iteritems()}
         supported_params = self.backend.get_parameters()
         for name, param in supported_params.iteritems():
-            value = self.instrument_parameters.get(name)
+            value = instrument_parameters.pop(name, None)
             param.set_value(self.params, value)
+        if instrument_parameters:
+            msg = 'Unexpected parameters for backend "{}": {}'
+            raise ConfigError(msg.format(self.instrument, instrument_parameters))
         self.backend.validate_parameters(self.params)
 
     def initialize(self, context):