diff --git a/aegisub/libaegisub/common/util.cpp b/aegisub/libaegisub/common/util.cpp
index 7c2191f6b..8f96b4715 100644
--- a/aegisub/libaegisub/common/util.cpp
+++ b/aegisub/libaegisub/common/util.cpp
@@ -17,6 +17,7 @@
 #include "../config.h"
 
 #include "libaegisub/util.h"
+#include "libaegisub/util_osx.h"
 
 #include "libaegisub/exception.h"
 
@@ -132,4 +133,12 @@ std::pair<size_t, size_t> ifind(std::string const& haystack, std::string const&
 	return ret;
 }
 
-} }
+}
+
+#ifndef __APPLE__
+namespace osx {
+AppNapDisabler::AppNapDisabler(std::string const& reason) { }
+AppNapDisabler::~AppNapDisabler() { }
+}
+#endif
+}
diff --git a/aegisub/libaegisub/include/libaegisub/util_osx.h b/aegisub/libaegisub/include/libaegisub/util_osx.h
index 5ec61a027..1e17e83d9 100644
--- a/aegisub/libaegisub/include/libaegisub/util_osx.h
+++ b/aegisub/libaegisub/include/libaegisub/util_osx.h
@@ -28,11 +28,17 @@
 /// When linking with this library, be sure to add '-framework CoreFoundation'
 /// to the GCC commandline.
 
-#ifdef __APPLE__
-
 #include <string>
 
 namespace agi {
+	namespace osx {
+		class AppNapDisabler {
+			void *handle;
+		public:
+			AppNapDisabler(std::string const& reason);
+			~AppNapDisabler();
+		};
+	}
     namespace util {
 /// @brief Get the full name of bundle.
 ///  @return Full name of bundle.
@@ -91,7 +97,5 @@ std::string OSX_GetBundleAuxillaryExecutablePath(std::string const& executableNa
 /// @param location URI of file
 /// @note If this is a FILE or DIRECTORY the path must be ABSOLUTE no 'file://'
 void OSX_OpenLocation(std::string const& location);
-    } // namespace io
+    } // namespace util
 } // namespace agi
-
-#endif
diff --git a/aegisub/libaegisub/osx/util.mm b/aegisub/libaegisub/osx/util.mm
index 9ed4f6274..28162902c 100644
--- a/aegisub/libaegisub/osx/util.mm
+++ b/aegisub/libaegisub/osx/util.mm
@@ -28,6 +28,22 @@ static std::string EmptyIfNil(NSString *string) {
 }
 
 namespace agi {
+	namespace osx {
+AppNapDisabler::AppNapDisabler(std::string const& reason) : handle(nullptr) {
+	auto processInfo = [NSProcessInfo processInfo];
+	if ([processInfo respondsToSelector:@selector(beginActivityWithOptions:reason:)])
+		handle = [[processInfo beginActivityWithOptions:NSActivityUserInitiatedAllowingIdleSystemSleep
+		                                         reason:[NSString stringWithUTF8String:reason.c_str()]]
+		          retain];
+}
+
+AppNapDisabler::~AppNapDisabler() {
+	auto processInfo = [NSProcessInfo processInfo];
+	if (handle && [processInfo respondsToSelector:@selector(endActivity:)])
+		[processInfo endActivity:(id)handle];
+	[(id)handle release];
+}
+	}
 	namespace util {
 
 std::string OSX_GetBundlePath() {
diff --git a/aegisub/src/dialog_progress.cpp b/aegisub/src/dialog_progress.cpp
index 8d37e7333..9f4cf5efa 100644
--- a/aegisub/src/dialog_progress.cpp
+++ b/aegisub/src/dialog_progress.cpp
@@ -26,6 +26,7 @@
 
 #include <libaegisub/dispatch.h>
 #include <libaegisub/exception.h>
+#include <libaegisub/util_osx.h>
 
 #include <atomic>
 #include <wx/button.h>
@@ -115,7 +116,9 @@ void DialogProgress::Run(std::function<void(agi::ProgressSink*)> task, int prior
 	DialogProgressSink ps(this);
 	this->ps = &ps;
 
+	auto current_title = from_wx(title->GetLabelText());
 	agi::dispatch::Background().Async([=]{
+		agi::osx::AppNapDisabler app_nap_disabler(current_title);
 		try {
 			task(this->ps);
 		}