diff --git a/.travis.yml b/.travis.yml
index 743f0ae..b6de8b3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -34,7 +34,7 @@ jobs:
 
     - os: osx
       name: "osx"
-      osx_image: xcode11.3
+      osx_image: xcode9.4
       env: ["CXX=clang++", "XCODE_VERSION=11.3.1"]
 
 install:
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 338e72c..59db089 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -59,8 +59,8 @@ if(CMAKE_COMPILER_IS_GNUCXX)
         message(FATAL_ERROR "GCC version must be at least 7.0!")
     endif()
 elseif(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-    if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS "10.0")
-        message(FATAL_ERROR "Clang version must be at least 10.0!")
+    if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS "9.0")
+        message(FATAL_ERROR "Clang version must be at least 9.0!")
     endif()
 else()
     message(WARNING "You are using an unsupported compiler! Compilation has only been tested with Clang and GCC.")