diff --git a/configure.ac b/configure.ac
index d04cd5d1..65637ee6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -69,7 +69,7 @@ AC_CONFIG_HEADERS([config.h])
 AC_CANONICAL_HOST
 AM_INIT_AUTOMAKE
 
-LIB_VERSION=`expr lib_current-lib_age`.lib_revision
+LIB_VERSION=`expr lib_current.lib_age`.lib_revision
 LIB_VERSION_INFO="lib_current:lib_revision:lib_age"
 
 # Set subsitution values for version stuff in Makefiles and anywhere else,