diff --git a/.bzrignore b/.bzrignore
new file mode 100644
index 0000000..b5bdf38
--- /dev/null
+++ b/.bzrignore
@@ -0,0 +1 @@
+termkey.h
diff --git a/Makefile b/Makefile
index a24a716..97441a1 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,10 @@ CFLAGS?=
 
 CFLAGS_DEBUG=
 
-SONAME=libtermkey.so.0
+VERSION_MAJOR=0
+VERSION_MINOR=0
+
+SONAME=libtermkey.so.$(VERSION_MAJOR)
 
 PREFIX=/usr/local
 LIBDIR=$(PREFIX)/lib
@@ -15,7 +18,12 @@ ifeq ($(DEBUG),1)
   CFLAGS_DEBUG=-ggdb -DDEBUG
 endif
 
-all: demo demo-async doc
+all: termkey.h demo demo-async doc
+
+termkey.h: termkey.h.in Makefile
+	sed -e 's/@@VERSION_MAJOR@@/$(VERSION_MAJOR)/g' \
+	    -e 's/@@VERSION_MINOR@@/$(VERSION_MINOR)/g' \
+	    $< >$@
 
 demo: libtermkey.so demo.c
 	$(CC) $(CFLAGS) $(CFLAGS_DEBUG) -o $@ $^
diff --git a/termkey.h b/termkey.h.in
similarity index 97%
rename from termkey.h
rename to termkey.h.in
index 4227518..4849923 100644
--- a/termkey.h
+++ b/termkey.h.in
@@ -4,6 +4,9 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+#define TERMKEY_VERSION_MAJOR @@VERSION_MAJOR@@
+#define TERMKEY_VERSION_MINOR @@VERSION_MINOR@@
+
 typedef enum {
   TERMKEY_SYM_UNKNOWN = -1,
   TERMKEY_SYM_NONE = 0,