diff --git a/doc/manual/installing.rst b/doc/manual/installing.rst
index 6e0270358..e15211791 100644
--- a/doc/manual/installing.rst
+++ b/doc/manual/installing.rst
@@ -192,7 +192,7 @@ and the ARTIQ kernels.
 
         $ mkdir build
         $ cd build
-        $ cmake .. -DCMAKE_INSTALL_PREFIX=/usr/local/llvm-or1k -DLLVM_TARGETS_TO_BUILD="OR1K;X86" -DLLVM_ENABLE_ASSERTIONS=ON
+        $ cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr/local/llvm-or1k -DLLVM_TARGETS_TO_BUILD="OR1K;X86" -DLLVM_ENABLE_ASSERTIONS=ON
         $ make -j4
         $ sudo make install