diff --git a/Libraries/WebSocket/RCTWebSocket.xcodeproj/project.pbxproj b/Libraries/WebSocket/RCTWebSocket.xcodeproj/project.pbxproj
index 8121ed0c108179..efb2609ad37b1a 100644
--- a/Libraries/WebSocket/RCTWebSocket.xcodeproj/project.pbxproj
+++ b/Libraries/WebSocket/RCTWebSocket.xcodeproj/project.pbxproj
@@ -435,8 +435,8 @@
 				EXECUTABLE_PREFIX = lib;
 				GCC_PREPROCESSOR_DEFINITIONS = (
 					"DEBUG=1",
+          "RCT_METRO_PORT=${RCT_METRO_PORT}",
 					"$(inherited)",
-					"RCT_METRO_PORT=${RCT_METRO_PORT}",
 				);
 				GCC_TREAT_WARNINGS_AS_ERRORS = NO;
 				OTHER_LDFLAGS = "-ObjC";
diff --git a/React/Base/RCTDefines.h b/React/Base/RCTDefines.h
index f700e0335080fa..0124bf340561db 100644
--- a/React/Base/RCTDefines.h
+++ b/React/Base/RCTDefines.h
@@ -74,6 +74,23 @@
 #define RCT_PROFILE RCT_DEV
 #endif
 
+/**
+ * Add the default Metro packager port number
+ */
+#ifndef RCT_METRO_PORT
+#define RCT_METRO_PORT 8081
+#else
+// test if RCT_METRO_PORT is empty
+#define RCT_METRO_PORT_DO_EXPAND(VAL)  VAL ## 1
+#define RCT_METRO_PORT_EXPAND(VAL)     RCT_METRO_PORT_DO_EXPAND(VAL)
+#if !defined(RCT_METRO_PORT) || (RCT_METRO_PORT_EXPAND(RCT_METRO_PORT) == 1)
+// Only here if RCT_METRO_PORT is not defined
+// OR RCT_METRO_PORT is the empty string
+#undef RCT_METRO_PORT
+#define RCT_METRO_PORT 8081
+#endif
+#endif
+
 /**
  * By default, only raise an NSAssertion in debug mode
  * (custom assert functions will still be called).
@@ -99,10 +116,3 @@ _Pragma("clang diagnostic ignored \"-Wunused-parameter\"") \
 RCT_EXTERN NSException *_RCTNotImplementedException(SEL, Class); \
 method NS_UNAVAILABLE { @throw _RCTNotImplementedException(_cmd, [self class]); } \
 _Pragma("clang diagnostic pop")
-
-/**
- * Add the default Metro packager port number 
- */
-#ifndef RCT_METRO_PORT
-#define RCT_METRO_PORT 8081
-#endif
diff --git a/React/React.xcodeproj/project.pbxproj b/React/React.xcodeproj/project.pbxproj
index 7e6ed8c1ec8e8a..a96223df6e0846 100644
--- a/React/React.xcodeproj/project.pbxproj
+++ b/React/React.xcodeproj/project.pbxproj
@@ -3957,7 +3957,7 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "export RCT_METRO_PORT=\"${RCT_METRO_PORT:-8081}\"\necho \"export RCT_METRO_PORT=${RCT_METRO_PORT}\" > \"${SRCROOT}/../scripts/.packager.env\"\nif [ -z \"${RCT_NO_LAUNCH_PACKAGER+xxx}\" ] ; then\n  if nc -w 5 -z localhost ${RCT_METRO_PORT} ; then\n    if ! curl -s \"http://localhost:${RCT_METRO_PORT}/status\" | grep -q \"packager-status:running\" ; then\n      echo \"Port ${RCT_METRO_PORT} already in use, packager is either not running or not running correctly\"\n      exit 2\n    fi\n  else\n    open \"$SRCROOT/../scripts/launchPackager.command\" || echo \"Can't start packager automatically\"\n  fi\nfi";
+			shellScript = "export RCT_METRO_PORT=\"${RCT_METRO_PORT:=8081}\"\necho \"export RCT_METRO_PORT=${RCT_METRO_PORT}\" > \"${SRCROOT}/../scripts/.packager.env\"\nif [ -z \"${RCT_NO_LAUNCH_PACKAGER+xxx}\" ] ; then\n  if nc -w 5 -z localhost ${RCT_METRO_PORT} ; then\n    if ! curl -s \"http://localhost:${RCT_METRO_PORT}/status\" | grep -q \"packager-status:running\" ; then\n      echo \"Port ${RCT_METRO_PORT} already in use, packager is either not running or not running correctly\"\n      exit 2\n    fi\n  else\n    open \"$SRCROOT/../scripts/launchPackager.command\" || echo \"Can't start packager automatically\"\n  fi\nfi";
 			showEnvVarsInLog = 0;
 		};
 		142C4F7F1B582EA6001F0B58 /* Include RCTJSCProfiler */ = {