diff --git a/CHANGELOG.md b/CHANGELOG.md
index b0e2cdec9..e2648fedb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file.
 This project uses the changelog in accordance with [keepchangelog](http://keepachangelog.com/). Please use this to write notable changes, which is not the same as git commit log...
 
 ## [unreleased][unreleased]
+ - Implemented AppNap API, fixing #283 and #627 OSX USB comm issues (AntiCat)
  - Added 'sc brute' - a naive SFI bruteforcer for contact smartcards (RDV40) (@iceman)
  - Change 'lf t55xx detectconfig' - now optional to persist settings to flashmem (RDV40) (@iceman)
  - Change 'hf mf csave' - now saves both EML/BIN formats (@iceman)
diff --git a/client/Makefile b/client/Makefile
index a1d06eb76..31c9c6a2d 100644
--- a/client/Makefile
+++ b/client/Makefile
@@ -34,9 +34,11 @@ LUAPLATFORM = generic
 platform = $(shell uname)
 ifneq (,$(findstring MINGW,$(platform))) 
     LUAPLATFORM = mingw
-    else
+else
 	ifeq ($(platform),Darwin)
     LUAPLATFORM = macosx
+	OBJCSRCS = util_darwin.m
+	LDFLAGS += -framework Foundation	
 else
     LUALIB +=  -ldl
     LDLIBS +=  -ltermcap -lncurses
@@ -223,6 +225,7 @@ QTGUISRCS = proxgui.cpp proxguiqt.cpp proxguiqt.moc.cpp guidummy.cpp
 
 COREOBJS = $(CORESRCS:%.c=$(OBJDIR)/%.o)
 CMDOBJS = $(CMDSRCS:%.c=$(OBJDIR)/%.o)
+OBJCOBJS = $(OBJCSRCS:%.m=$(OBJDIR)/%.o)
 ZLIBOBJS = $(ZLIBSRCS:%.c=$(OBJDIR)/%.o)
 MULTIARCHOBJS = $(MULTIARCHSRCS:%.c=$(OBJDIR)/%_NOSIMD.o) \
 			$(MULTIARCHSRCS:%.c=$(OBJDIR)/%_MMX.o) \
@@ -249,7 +252,7 @@ endif
 
 BINS = proxmark3 flasher fpga_compress
 WINBINS = $(patsubst %, %.exe, $(BINS))
-CLEAN = $(BINS) $(WINBINS) $(COREOBJS) $(CMDOBJS) $(ZLIBOBJS) $(QTGUIOBJS) $(MULTIARCHOBJS) $(OBJDIR)/*.o *.moc.cpp ui/ui_overlays.h lualibs/usb_cmd.lua lualibs/mf_default_keys.lua
+CLEAN = $(BINS) $(WINBINS) $(COREOBJS) $(CMDOBJS) $(OBJCOBJS) $(ZLIBOBJS) $(QTGUIOBJS) $(MULTIARCHOBJS) $(OBJDIR)/*.o *.moc.cpp ui/ui_overlays.h lualibs/usb_cmd.lua lualibs/mf_default_keys.lua
 
 # need to assign dependancies to build these first...
 all: lua_build $(BINS) 
@@ -258,10 +261,10 @@ all-static: LDLIBS:=-static $(LDLIBS)
 all-static: proxmark3 flasher fpga_compress
 
 proxmark3: LDLIBS+=$(LUALIB) $(QTLDLIBS)
-proxmark3: $(OBJDIR)/proxmark3.o $(COREOBJS) $(CMDOBJS) $(QTGUIOBJS) $(MULTIARCHOBJS) $(ZLIBOBJS) lualibs/usb_cmd.lua lualibs/mf_default_keys.lua
-	$(LD) $(LDFLAGS) $(OBJDIR)/proxmark3.o $(COREOBJS) $(CMDOBJS) $(QTGUIOBJS) $(MULTIARCHOBJS) $(ZLIBOBJS) $(LDLIBS)  -o $@
+proxmark3: $(OBJDIR)/proxmark3.o $(COREOBJS) $(CMDOBJS) $(OBJCOBJS) $(QTGUIOBJS) $(MULTIARCHOBJS) $(ZLIBOBJS) lualibs/usb_cmd.lua lualibs/mf_default_keys.lua
+	$(LD) $(LDFLAGS) $(OBJDIR)/proxmark3.o $(COREOBJS) $(CMDOBJS) $(OBJCOBJS) $(QTGUIOBJS) $(MULTIARCHOBJS) $(ZLIBOBJS) $(LDLIBS)  -o $@
 	
-flasher: $(OBJDIR)/flash.o $(OBJDIR)/flasher.o $(COREOBJS)
+flasher: $(OBJDIR)/flash.o $(OBJDIR)/flasher.o $(COREOBJS) $(OBJCOBJS)
 	$(LD) $(LDFLAGS) $^ $(LDLIBS) -o $@
 
 fpga_compress: $(OBJDIR)/fpga_compress.o $(ZLIBOBJS)
@@ -325,6 +328,11 @@ $(OBJDIR)/%.o : %.cpp $(OBJDIR)/%.d
 	$(CXX) $(DEPFLAGS) $(CXXFLAGS) $(QTINCLUDES) -c -o $@ $<
 	$(POSTCOMPILE)
 
+%.o: %.m
+$(OBJDIR)/%.o : %.m $(OBJDIR)/%.d
+	$(CC) $(DEPFLAGS) $(CFLAGS) -c -o $@ $<
+	$(POSTCOMPILE)
+	
 #$(CMDOBJS) $(COREOBJS): $(notdir $(%.c)) %.d
 #	$(CC) $(DEPFLAGS) $(CFLAGS) -c -o $@ $<
 #	$(POSTCOMPILE)
@@ -339,6 +347,7 @@ $(OBJDIR)/%.o : %.cpp $(OBJDIR)/%.d
 
 DEPENDENCY_FILES = $(patsubst %.c, $(OBJDIR)/%.d, $(CORESRCS) $(CMDSRCS) $(ZLIBSRCS) $(MULTIARCHSRCS)) \
 	$(patsubst %.cpp, $(OBJDIR)/%.d, $(QTGUISRCS)) \
+	$(patsubst %.m, $(OBJDIR)/%.d, $(OBJCSRCS)) \
 	$(OBJDIR)/proxmark3.d $(OBJDIR)/flash.d $(OBJDIR)/flasher.d $(OBJDIR)/fpga_compress.d
 
 $(DEPENDENCY_FILES): ;
diff --git a/client/comms.c b/client/comms.c
index 21d9ad4a7..e297e9057 100644
--- a/client/comms.c
+++ b/client/comms.c
@@ -242,6 +242,11 @@ __attribute__((force_align_arg_pointer))
 	UsbCommand *prx = &rx;
 	
 	//int counter_to_offline = 0;
+
+#if defined(__MACH__) && defined(__APPLE__)
+	disableAppNap("Proxmark3 polling UART");
+#endif
+	
 	
 	while (conn->run) {
 		rxlen = 0;
@@ -288,6 +293,11 @@ __attribute__((force_align_arg_pointer))
 	// when this reader thread dies, we close the serial port.
 	uart_close(sp);
 	sp = NULL;
+
+#if defined(__MACH__) && defined(__APPLE__)
+	enableAppNap();
+#endif
+
 	
 	pthread_exit(NULL);
 	return NULL;
diff --git a/client/comms.h b/client/comms.h
index eba0d45d5..e311f5e0c 100644
--- a/client/comms.h
+++ b/client/comms.h
@@ -21,6 +21,7 @@
 #include "common.h"
 #include "util_posix.h"
 #include "util.h" 
+#include "util_darwin.h"
 
 #if defined(__linux__) && !defined(NO_UNLINK)
 #include <unistd.h>		// for unlink()
diff --git a/client/util_darwin.c b/client/util_darwin.c
new file mode 100644
index 000000000..d07ebebc4
--- /dev/null
+++ b/client/util_darwin.c
@@ -0,0 +1,40 @@
+//-----------------------------------------------------------------------------
+// (c) 2018 AntiCat
+//
+// This code is licensed to you under the terms of the GNU GPL, version 2 or,
+// at your option, any later version. See the LICENSE.txt file for the text of
+// the license.
+//-----------------------------------------------------------------------------
+// macOS framework bindings
+//-----------------------------------------------------------------------------
+
+#import "util_darwin.h"
+
+#import <Foundation/NSString.h>
+#import <Foundation/NSProcessInfo.h>
+
+static id activity = nil;
+
+//OS X Version 10.10 is defined in OS X 10.10 and later
+#if defined(MAC_OS_X_VERSION_10_10)
+void disableAppNap(const char* reason) {
+	if(activity == nil) {
+		//NSLog(@"disableAppNap: %@", @(reason));
+		activity = [[NSProcessInfo processInfo] beginActivityWithOptions:NSActivityBackground reason:@(reason)];
+		[activity retain];
+	}
+}
+
+void enableAppNap() {
+	if(activity != nil) {
+		//NSLog(@"enableAppNap");
+		[[NSProcessInfo processInfo] endActivity:activity];
+		[activity release];
+		activity = nil;
+	}
+}
+
+#else
+void disableAppNap(const char* reason) { }
+void enableAppNap() { }
+#endif
diff --git a/client/util_darwin.h b/client/util_darwin.h
new file mode 100644
index 000000000..923a4dfc0
--- /dev/null
+++ b/client/util_darwin.h
@@ -0,0 +1,17 @@
+//-----------------------------------------------------------------------------
+// (c) 2018 AntiCat
+//
+// This code is licensed to you under the terms of the GNU GPL, version 2 or,
+// at your option, any later version. See the LICENSE.txt file for the text of
+// the license.
+//-----------------------------------------------------------------------------
+// macOS framework bindings
+//-----------------------------------------------------------------------------
+
+#ifndef UTIL_DARWIN_H__
+#define UTIL_DARWIN_H__
+
+void disableAppNap(const char* reason);
+void enableAppNap();
+
+#endif
\ No newline at end of file