diff --git a/lib/fl2.cc b/lib/fl2.cc
index 98d2ab21..b4c1ff8c 100644
--- a/lib/fl2.cc
+++ b/lib/fl2.cc
@@ -25,7 +25,15 @@ static void upgradeFluxFile(FluxFileProto& proto)
 
         proto.set_version(FluxFileVersion::VERSION_2);
     }
-    if (proto.version() > FluxFileVersion::VERSION_2)
+
+	if (proto.version() == FluxFileVersion::VERSION_2)
+	{
+		proto.mutable_drive()->set_rotational_period_ms(
+			proto.rotational_period_ms());
+        proto.set_version(FluxFileVersion::VERSION_3);
+	}
+
+    if (proto.version() > FluxFileVersion::VERSION_3)
         error(
             "this is a version {} flux file, but this build of the client can "
             "only handle up to version {} --- please upgrade",
@@ -57,7 +65,7 @@ FluxFileProto loadFl2File(const std::string filename)
 void saveFl2File(const std::string filename, FluxFileProto& proto)
 {
     proto.set_magic(FluxMagic::MAGIC);
-    proto.set_version(FluxFileVersion::VERSION_2);
+    proto.set_version(FluxFileVersion::VERSION_3);
 
     std::ofstream of(filename, std::ios::out | std::ios::binary);
     if (!proto.SerializeToOstream(&of))
diff --git a/lib/fl2.proto b/lib/fl2.proto
index 104b0f54..190246ab 100644
--- a/lib/fl2.proto
+++ b/lib/fl2.proto
@@ -1,5 +1,7 @@
 syntax = "proto2";
 
+import "lib/drive.proto";
+
 enum FluxMagic {
 	MAGIC = 0x466c7578;
 }
@@ -7,6 +9,7 @@ enum FluxMagic {
 enum FluxFileVersion {
 	VERSION_1 = 1;
 	VERSION_2 = 2;
+	VERSION_3 = 3;
 }
 
 message TrackFluxProto {
@@ -19,6 +22,7 @@ message FluxFileProto {
 	optional int32 magic = 1;
 	optional FluxFileVersion version = 2;
 	repeated TrackFluxProto track = 3;
-	optional double rotational_period_ms = 4;
+	optional double rotational_period_ms = 4 [ deprecated=true ];
+	optional DriveProto drive = 5;
 }
 
diff --git a/lib/fluxsink/fl2fluxsink.cc b/lib/fluxsink/fl2fluxsink.cc
index a01948d7..2abff8e4 100644
--- a/lib/fluxsink/fl2fluxsink.cc
+++ b/lib/fluxsink/fl2fluxsink.cc
@@ -43,6 +43,7 @@ public:
                 track->add_flux(fluxBytes);
         }
 
+		proto.mutable_drive()->MergeFrom(config.drive());
         saveFl2File(_filename, proto);
     }
 
diff --git a/lib/fluxsource/fl2fluxsource.cc b/lib/fluxsource/fl2fluxsource.cc
index f6f48267..73d8fa90 100644
--- a/lib/fluxsource/fl2fluxsource.cc
+++ b/lib/fluxsource/fl2fluxsource.cc
@@ -36,6 +36,10 @@ public:
     Fl2FluxSource(const Fl2FluxSourceProto& config): _config(config)
     {
         _proto = loadFl2File(_config.filename());
+
+		if (::config.has_drive())
+			warning("FLUX: overriding drive configuration with flux file contents");
+		::config.mutable_drive()->MergeFrom(_proto.drive());
     }
 
 public:
diff --git a/lib/globals.cc b/lib/globals.cc
index b49fbc2e..0b3a6e5e 100644
--- a/lib/globals.cc
+++ b/lib/globals.cc
@@ -1,4 +1,5 @@
-#include "globals.h"
+#include "lib/globals.h"
+#include "lib/logger.h"
 #include <sys/time.h>
 #include <stdarg.h>
 
@@ -8,4 +9,11 @@ double getCurrentTime(void)
     gettimeofday(&tv, NULL);
 
     return double(tv.tv_sec) + tv.tv_usec / 1000000.0;
-}
\ No newline at end of file
+}
+
+void warning(const std::string msg)
+{
+	log(msg);
+	fmt::print("Warning: {}\n", msg);
+}
+
diff --git a/lib/globals.h b/lib/globals.h
index 19305b96..c3ad39d4 100644
--- a/lib/globals.h
+++ b/lib/globals.h
@@ -49,6 +49,14 @@ inline void error(fmt::string_view fstr, const Args&... args)
 	throw ErrorException { fmt::format(fstr, args...) };
 }
 
+extern void warning(const std::string msg);
+
+template <typename... Args>
+inline void warning(fmt::string_view fstr, const Args&... args)
+{
+	warning(fmt::format(fstr, args...));
+}
+
 template <class... Ts> struct overloaded : Ts...  { using Ts::operator()...; };
 template <class... Ts> overloaded(Ts...) -> overloaded<Ts...>;