diff --git a/mps/code/mps.xcodeproj/project.pbxproj b/mps/code/mps.xcodeproj/project.pbxproj
index 0980991ffa2..b01a7a8de6e 100644
--- a/mps/code/mps.xcodeproj/project.pbxproj
+++ b/mps/code/mps.xcodeproj/project.pbxproj
@@ -5534,7 +5534,7 @@
 				GCC_WARN_UNUSED_LABEL = YES;
 				GCC_WARN_UNUSED_PARAMETER = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				MACOSX_DEPLOYMENT_TARGET = 10.4;
+				MACOSX_DEPLOYMENT_TARGET = 10.6;
 				SDKROOT = macosx;
 				SYMROOT = xc;
 				WARNING_CFLAGS = (
@@ -5973,7 +5973,7 @@
 				GCC_WARN_UNUSED_LABEL = YES;
 				GCC_WARN_UNUSED_PARAMETER = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				MACOSX_DEPLOYMENT_TARGET = 10.4;
+				MACOSX_DEPLOYMENT_TARGET = 10.6;
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = macosx;
 				SYMROOT = xc;
@@ -6032,7 +6032,7 @@
 				GCC_WARN_UNUSED_LABEL = YES;
 				GCC_WARN_UNUSED_PARAMETER = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				MACOSX_DEPLOYMENT_TARGET = 10.4;
+				MACOSX_DEPLOYMENT_TARGET = 10.6;
 				SDKROOT = macosx;
 				SYMROOT = xc;
 				WARNING_CFLAGS = (
diff --git a/mps/manual/source/release.rst b/mps/manual/source/release.rst
index dc52316d3d5..664333c068a 100644
--- a/mps/manual/source/release.rst
+++ b/mps/manual/source/release.rst
@@ -12,6 +12,10 @@ Release 1.118.0
 New features
 ............
 
+#. The MPS now supports macOS 10.6 (Snow Leopard) or later; it no
+   longer supports 10.4 (Tiger) and 10.5 (Leopard). This is because
+   Xcode 10.0 no longer supports these versions.
+
 #. The arena's :term:`spare commit limit` is now expressed as a
    fraction of the :term:`committed <mapped>` memory (rather than a
    fixed size, as previously). This allows the :term:`spare committed
diff --git a/mps/readme.txt b/mps/readme.txt
index 115ec3d01d3..0fef16b9a56 100644
--- a/mps/readme.txt
+++ b/mps/readme.txt
@@ -80,7 +80,7 @@ The MPS is currently supported for deployment on:
 
 - FreeBSD 7 or later, on IA-32 and x86-64, using GCC or Clang/LLVM;
 
-- macOS 10.4 or later, on IA-32 and x86-64, using Clang/LLVM.
+- macOS 10.6 or later, on IA-32 and x86-64, using Clang/LLVM.
 
 The MPS is highly portable and has run on many other processors and
 operating systems in the past (see `Building the MPS