diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0d81a57fd..7e73a6e50 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -224,8 +224,9 @@ if(GTSAM_USE_SYSTEM_EIGEN)
     set(GTSAM_EIGEN_INCLUDE_PREFIX "${EIGEN3_INCLUDE_DIR}")
 	
 	# check if MKL is also enabled - can have one or the other, but not both!
-	if(EIGEN_USE_MKL_ALL)
-	  message(FATAL_ERROR "MKL cannot be used together with system-installed Eigen, as MKL support relies on patches which are not yet in the system-installed Eigen. Disable either GTSAM_USE_SYSTEM_EIGEN or GTSAM_WITH_EIGEN_MKL")
+	# Note: Eigen >= v3.2.5 includes our patches
+	if(EIGEN_USE_MKL_ALL AND (EIGEN3_VERSION VERSION_LESS 3.2.5))
+	  message(FATAL_ERROR "MKL requires at least Eigen 3.2.5, and your system appears to have an older version. Disable GTSAM_USE_SYSTEM_EIGEN to use GTSAM's copy of Eigen, or disable GTSAM_WITH_EIGEN_MKL")
 	endif()
 else()
 	# Use bundled Eigen include path. 
diff --git a/gtsam/base/Matrix.cpp b/gtsam/base/Matrix.cpp
index 740699d4b..d92be12f5 100644
--- a/gtsam/base/Matrix.cpp
+++ b/gtsam/base/Matrix.cpp
@@ -704,11 +704,9 @@ void inplace_QR(Matrix& A){
   HCoeffsType hCoeffs(size);
   RowVectorType temp(cols);
 
-#ifdef GTSAM_USE_SYSTEM_EIGEN
-  // System-Eigen is used, and MKL is off
+#if !EIGEN_VERSION_AT_LEAST(3,2,5)
   Eigen::internal::householder_qr_inplace_blocked<Matrix, HCoeffsType>(A, hCoeffs, 48, temp.data());
 #else
-  // Patched Eigen is used, and MKL is either on or off
   Eigen::internal::householder_qr_inplace_blocked<Matrix, HCoeffsType>::run(A, hCoeffs, 48, temp.data());
 #endif