diff --git a/pyperformance/_benchmark.py b/pyperformance/_benchmark.py
index cd51dfe6..516fbbd1 100644
--- a/pyperformance/_benchmark.py
+++ b/pyperformance/_benchmark.py
@@ -252,7 +252,7 @@ def _resolve_restricted_opts(opts):
         if opt.startswith(FLAG + '='):
             idx = i + 1
             resolved.append(FLAG)
-            resolved.append(opt.partition('=')[-2])
+            resolved.append(opt.partition('=')[-1])
             resolved.extend(opts[idx:])
             break
         elif opt == FLAG:
diff --git a/pyperformance/cli.py b/pyperformance/cli.py
index 95f78429..ae30a682 100644
--- a/pyperformance/cli.py
+++ b/pyperformance/cli.py
@@ -60,6 +60,8 @@ def parse_args():
     cmd.add_argument("--append", metavar="FILENAME",
                      help="Add runs to an existing file, or create it "
                      "if it doesn't exist")
+    cmd.add_argument("--track-energy", action="store_true",
+                     help="Track energy instead of wall clock time.")
     filter_opts(cmd)
 
     # show
diff --git a/pyperformance/data-files/requirements.txt b/pyperformance/data-files/requirements.txt
index f59bc323..c94d8fe5 100644
--- a/pyperformance/data-files/requirements.txt
+++ b/pyperformance/data-files/requirements.txt
@@ -10,7 +10,7 @@ psutil==5.8.0
     # via -r requirements.in
 pyparsing==3.0.6
     # via packaging
-pyperf==2.3.0
+pyperf @ file:///home/cappadokes/code/pyperf
     # via -r requirements.in
 toml==0.10.2
     # via -r requirements.in
diff --git a/pyperformance/run.py b/pyperformance/run.py
index 8e196547..871ade01 100644
--- a/pyperformance/run.py
+++ b/pyperformance/run.py
@@ -190,7 +190,26 @@ def get_pyperf_opts(options):
         opts.append('--affinity=%s' % options.affinity)
     if options.track_memory:
         opts.append('--track-memory')
-    if options.inherit_environ:
+    if options.inherit_environ or options.track_energy:
+        # In the track_energy case, pyperf will need
+        # a couple of env variables to work. We save
+        # the user from manual insertion of --inherit-environ.
+        if options.track_energy:
+            if options.inherit_environ is None:
+                options.inherit_environ = []
+            from os import environ as curr_env
+            env = curr_env
+            try:
+                lib = env['READEN']
+                f = env['ENFILE']
+                ld = env['LD_LIBRARY_PATH']
+                options.inherit_environ.append('READEN')
+                options.inherit_environ.append('ENFILE')
+                options.inherit_environ.append('LD_LIBRARY_PATH')
+            except:
+                raise OSError('--track-energy needs READEN, ENFILE environment variables to work.')
         opts.append('--inherit-environ=%s' % ','.join(options.inherit_environ))
-
+    if options.track_energy:
+        opts.append('--track-energy')
+            
     return opts