diff --git a/qmake/qmake.pro b/qmake/qmake.pro
index 641943a..4fe957d 100644
--- a/qmake/qmake.pro
+++ b/qmake/qmake.pro
@@ -40,6 +40,7 @@ DEFINES += _GNU_SOURCE DEBUG _FILE_OFFSET_BITS=64 _USE_MATH_DEFINES
 
 # Latest X-Plane APIs. No legacy support needed.
 DEFINES += XPLM200 XPLM210
+DEFINES += XRAAS2_BUILD_VERSION=\'\"$$system("git rev-parse --short HEAD")\"\'
 
 # Aircraft-specific defines
 DEFINES += ACF_TYPE=$$[ACF_TYPE]
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 621e0ef..6659d8b 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -68,6 +68,14 @@ else()
 	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DAPL=0 -DIBM=0 -DLIN=1")
 endif()
 
+# Yes, we need to strip a trailing newline from command output. CMake is
+# "smart" like that...
+execute_process(COMMAND git rev-parse --short HEAD
+    OUTPUT_VARIABLE XRAAS2_BUILD_VERSION)
+string(REGEX REPLACE "\n$" "" XRAAS2_BUILD_VERSION "${XRAAS2_BUILD_VERSION}")
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} \
+    -DXRAAS2_BUILD_VERSION='\"${XRAAS2_BUILD_VERSION}\"'")
+
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fvisibility=hidden")
 
 #linking
diff --git a/src/xraas2.h b/src/xraas2.h
index 342a2c6..c88e4e7 100644
--- a/src/xraas2.h
+++ b/src/xraas2.h
@@ -30,7 +30,7 @@
 extern "C" {
 #endif
 
-#define	XRAAS2_VERSION			"2.1"
+#define	XRAAS2_VERSION			"2.1-" XRAAS2_BUILD_VERSION
 #define	TATL_FIELD_ELEV_UNSET		-1000000
 #define	RWY_PROXIMITY_TIME_FACT		2		/* seconds */
 #define	ARPT_LOAD_LIMIT			NM2MET(8)	/* meters */