diff --git a/External/catch/CMakeLists.txt b/External/catch/CMakeLists.txt
index 91d9ffa87..a22395569 100644
--- a/External/catch/CMakeLists.txt
+++ b/External/catch/CMakeLists.txt
@@ -3,20 +3,23 @@ add_custom_target(catch ALL)
 if(NOT DEFINED CATCH_DIR)
   set(CATCH_DIR "${CMAKE_CURRENT_SOURCE_DIR}/catch")
 endif()
-if(NOT EXISTS "${CATCH_DIR}/catch.hpp")
-    message("-- Catch not found in ${CATCH_DIR}")
-    include(RDKitUtils)
-    set(RELEASE_NO "2.1.2")
-    downloadAndCheckMD5("https://github.com/catchorg/Catch2/archive/v${RELEASE_NO}.tar.gz"
-          "${CMAKE_CURRENT_SOURCE_DIR}/master.tar.gz"
-          "4c5740d7446d9b4e3735dcff0951aaca")
-    execute_process(COMMAND ${CMAKE_COMMAND} -E tar zxf
-      ${CMAKE_CURRENT_SOURCE_DIR}/master.tar.gz
-      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
-    file(RENAME "Catch2-${RELEASE_NO}" "${CATCH_DIR}")
-    set(CATCH_INCLUDE_DIR "${CATCH_DIR}/single_include" PARENT_SCOPE)
-else()
+if(EXISTS "${CATCH_DIR}/catch.hpp")
   message("-- Found Catch2: ${CATCH_DIR}")
   set(CATCH_INCLUDE_DIR "${CATCH_DIR}" PARENT_SCOPE)
+elseif(EXISTS "${CATCH_DIR}/single_include/catch.hpp")
+  message("-- Found Catch2 source in ${CATCH_DIR}")
+  set(CATCH_INCLUDE_DIR "${CATCH_DIR}/single_include" PARENT_SCOPE)
+else()
+  message("-- Catch not found in ${CATCH_DIR}")
+  include(RDKitUtils)
+  set(RELEASE_NO "2.1.2")
+  downloadAndCheckMD5("https://github.com/catchorg/Catch2/archive/v${RELEASE_NO}.tar.gz"
+        "${CMAKE_CURRENT_SOURCE_DIR}/master.tar.gz"
+        "4c5740d7446d9b4e3735dcff0951aaca")
+  execute_process(COMMAND ${CMAKE_COMMAND} -E tar zxf
+    ${CMAKE_CURRENT_SOURCE_DIR}/master.tar.gz
+    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
+  file(RENAME "Catch2-${RELEASE_NO}" "${CATCH_DIR}")
+  set(CATCH_INCLUDE_DIR "${CATCH_DIR}/single_include" PARENT_SCOPE)
 endif()