diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 80525960c..82aa0670d 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -62,7 +62,7 @@ endif()
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake/Modules/")
 
 # Initialize CXXFLAGS.
-set(CMAKE_CXX_FLAGS                "-Wall -Wextra -std=c++11 ${LEAN_EXTRA_CXX_FLAGS}")
+set(CMAKE_CXX_FLAGS                "-Wall -Wextra -std=c++11 ${LEAN_EXTRA_CXX_FLAGS} -DLEAN_BUILD_TYPE=\"${CMAKE_BUILD_TYPE}\"")
 set(CMAKE_CXX_FLAGS_DEBUG          "-g -DLEAN_DEBUG -DLEAN_TRACE")
 set(CMAKE_CXX_FLAGS_MINSIZEREL     "-Os -DNDEBUG")
 set(CMAKE_CXX_FLAGS_RELEASE        "-O3 -DNDEBUG")
diff --git a/src/shell/lean.cpp b/src/shell/lean.cpp
index cd275edfd..8f4f7e030 100644
--- a/src/shell/lean.cpp
+++ b/src/shell/lean.cpp
@@ -61,8 +61,13 @@ static void on_ctrl_c(int ) {
     lean::request_interrupt();
 }
 
+#define XSTR(x) #x
+#define STR(x) XSTR(x)
+
 static void display_header(std::ostream & out) {
-    out << "Lean (version " << LEAN_VERSION_MAJOR << "." << LEAN_VERSION_MINOR << ", commit " << std::string(g_githash).substr(0, 12) << ")\n";
+    out << "Lean (version " << LEAN_VERSION_MAJOR << "." << LEAN_VERSION_MINOR
+        << ", commit " << std::string(g_githash).substr(0, 12)
+        << ", " << STR(LEAN_BUILD_TYPE) << ")\n";
 }
 
 static void display_help(std::ostream & out) {