diff --git a/Hammerspoon.xcodeproj/project.pbxproj b/Hammerspoon.xcodeproj/project.pbxproj
index ee9f6fb88..fd76afd94 100644
--- a/Hammerspoon.xcodeproj/project.pbxproj
+++ b/Hammerspoon.xcodeproj/project.pbxproj
@@ -896,7 +896,7 @@
 		22613FE51F297B9B00E05E11 /* init.lua */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; name = init.lua; path = extensions/dialog/init.lua; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.lua; };
 		22613FF11F297E0D00E05E11 /* libdialog.dylib */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.dylib"; includeInIndex = 0; path = libdialog.dylib; sourceTree = BUILT_PRODUCTS_DIR; };
 		22E4D7F71FA7485A00C8CF5C /* internal.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; name = internal.m; path = extensions/midi/internal.m; sourceTree = SOURCE_ROOT; };
-		22E4D7F81FA7485A00C8CF5C /* init.lua */ = {isa = PBXFileReference; lastKnownFileType = text; name = init.lua; path = extensions/midi/init.lua; sourceTree = SOURCE_ROOT; xcLanguageSpecificationIdentifier = xcode.lang.lua; };
+		22E4D7F81FA7485A00C8CF5C /* init.lua */ = {isa = PBXFileReference; lastKnownFileType = text; name = init.lua; path = extensions/midi/init.lua; sourceTree = SOURCE_ROOT; };
 		22E4D8021FA7488900C8CF5C /* libmidi.dylib */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.dylib"; includeInIndex = 0; path = libmidi.dylib; sourceTree = BUILT_PRODUCTS_DIR; };
 		22E4D8071FA74BDA00C8CF5C /* libMIKMIDI.a */ = {isa = PBXFileReference; explicitFileType = archive.ar; path = libMIKMIDI.a; sourceTree = BUILT_PRODUCTS_DIR; };
 		4C3D55A91C7F05D00023B633 /* init.lua */ = {isa = PBXFileReference; lastKnownFileType = text; path = init.lua; sourceTree = "<group>"; };
diff --git a/extensions/midi/internal.m b/extensions/midi/internal.m
index 7a48a834f..01ad7a022 100755
--- a/extensions/midi/internal.m
+++ b/extensions/midi/internal.m
@@ -455,6 +455,15 @@ static int midi_callback(lua_State *L) {
         // Setup MIDI Device End Point:
         //
         NSArray *source = [device.entities valueForKeyPath:@"@unionOfArrays.sources"];
+        if (source.count == 0) {
+            //
+            // This shouldn't happen, but if it does, catch the error:
+            //
+            [skin logError:[NSString stringWithFormat:@"%s:callback error:%@", USERDATA_TAG, @"No MIDI Device End Points detected."]] ;
+            wrapper.callbackToken = nil;
+            lua_pushvalue(L, 1);
+            return 1;
+        }
         MIKMIDISourceEndpoint *endpoint = [source objectAtIndex:0];
         
         //