diff --git a/Cartfile b/Cartfile
index 543e2fd94..480add23b 100644
--- a/Cartfile
+++ b/Cartfile
@@ -1,3 +1,7 @@
-github "mxcl/PromiseKit"
+# Avoid PromiseKit 5 for now.
+# From the maintainer:
+# > PromiseKit 5 has been released, but is not yet fully documented, 
+# > so we advise sticking with version 4 for the time being.
+github "mxcl/PromiseKit" ~> 4.0
 github "TheLevelUp/ZXingObjC"
 
diff --git a/Cartfile.resolved b/Cartfile.resolved
index d8b568bad..c2bc915b5 100644
--- a/Cartfile.resolved
+++ b/Cartfile.resolved
@@ -1,2 +1,2 @@
-github "TheLevelUp/ZXingObjC" "3.2.1"
-github "mxcl/PromiseKit" "4.4.1"
+github "TheLevelUp/ZXingObjC" "3.2.2"
+github "mxcl/PromiseKit" "4.5.0"
diff --git a/Carthage b/Carthage
index 4c73f1a2f..a172c59aa 160000
--- a/Carthage
+++ b/Carthage
@@ -1 +1 @@
-Subproject commit 4c73f1a2f0c0bceca7f0fb6777adb81c99ec0d4f
+Subproject commit a172c59aa282c4e0cb43c8134abc5b237d3ca885