diff --git a/cmake/ipo.cmake b/cmake/ipo.cmake
index b760f3cddf..ce54b0e381 100644
--- a/cmake/ipo.cmake
+++ b/cmake/ipo.cmake
@@ -9,7 +9,9 @@ function(ipo_enable IPO_ENABLED_BUILDS)
     check_ipo_supported(RESULT IPO_SUPPORTED OUTPUT IPO_LOG)
 
     set(IPO_BUILD_ENABLED OFF PARENT_SCOPE)
-    if(IPO_SUPPORTED AND ${CMAKE_BUILD_TYPE} IN_LIST IPO_ENABLED_BUILDS)
+    if(NOT CMAKE_BUILD_TYPE)
+        message(STATUS "CMAKE_BUILD_TYPE not explicitly set. Not enabling IPO.")
+    elseif(IPO_SUPPORTED AND ${CMAKE_BUILD_TYPE} IN_LIST IPO_ENABLED_BUILDS)
         if(NOT DISABLE_IPO)
             message(STATUS "IPO supported and enabled in ${CMAKE_BUILD_TYPE}.")
             set(IPO_BUILD_ENABLED ON PARENT_SCOPE)