diff --git a/src/octoprint/gcodefiles.py b/src/octoprint/gcodefiles.py
index 56e1ed2e..34860bad 100644
--- a/src/octoprint/gcodefiles.py
+++ b/src/octoprint/gcodefiles.py
@@ -293,7 +293,7 @@ class GcodeManager:
 					os.remove(stlPath)
 			else:
 				slicingStop = time.time()
-				eventManager().fire(Events.SLICING_DONE, {"stl": self._getBasicFilename(stlPath), "gcode": self._getBasicFilename(gcodePath), "time": "%.2f" % (slicingStop - slicingStart)})
+				eventManager().fire(Events.SLICING_DONE, {"stl": self._getBasicFilename(stlPath), "gcode": self._getBasicFilename(gcodePath), "time": slicingStop - slicingStart})
 				self.processGcode(gcodePath, destination, uploadCallback)
 
 		eventManager().fire(Events.SLICING_STARTED, {"stl": self._getBasicFilename(absolutePath), "gcode": self._getBasicFilename(gcodePath)})
diff --git a/src/octoprint/static/js/app/dataupdater.js b/src/octoprint/static/js/app/dataupdater.js
index 1df395fa..b7019ecf 100644
--- a/src/octoprint/static/js/app/dataupdater.js
+++ b/src/octoprint/static/js/app/dataupdater.js
@@ -127,7 +127,7 @@ function DataUpdater(loginStateViewModel, connectionViewModel, printerStateViewM
                         gcodeUploadProgress.removeClass("progress-striped").removeClass("active");
                         gcodeUploadProgressBar.css("width", "0%");
                         gcodeUploadProgressBar.text("");
-                        $.pnotify({title: "Slicing done", text: "Sliced " + payload.stl + " to " + payload.gcode + ", took " + payload.time + " seconds"});
+                        $.pnotify({title: "Slicing done", text: "Sliced " + payload.stl + " to " + payload.gcode + ", took " + _.sprintf("%.2f", payload.time) + " seconds"});
                         gcodeFilesViewModel.requestData(payload.gcode);
                     } else if (type == "SlicingFailed") {
                         gcodeUploadProgress.removeClass("progress-striped").removeClass("active");
@@ -142,7 +142,7 @@ function DataUpdater(loginStateViewModel, connectionViewModel, printerStateViewM
                         gcodeUploadProgress.removeClass("progress-striped").removeClass("active");
                         gcodeUploadProgressBar.css("width", "0%");
                         gcodeUploadProgressBar.text("");
-                        $.pnotify({title: "Streaming done", text: "Streamed " + payload.local + " to " + payload.remote + " on SD, took " + payload.time + " seconds"});
+                        $.pnotify({title: "Streaming done", text: "Streamed " + payload.local + " to " + payload.remote + " on SD, took " + _.sprintf("%.2f", payload.time) + " seconds"});
                         gcodeFilesViewModel.requestData(payload.remote, "sdcard");
                     }
                     break;
diff --git a/src/octoprint/util/comm.py b/src/octoprint/util/comm.py
index afd81496..ac25b15b 100644
--- a/src/octoprint/util/comm.py
+++ b/src/octoprint/util/comm.py
@@ -927,7 +927,7 @@ class MachineCom(object):
 					payload = {
 						"local": self._currentFile.getLocalFilename(),
 						"remote": self._currentFile.getRemoteFilename(),
-						"time": "%.2f" % (time.time() - self._currentFile.getStartTime())
+						"time": time.time() - self._currentFile.getStartTime()
 					}
 
 					self._currentFile = None