diff --git a/configure.ac b/configure.ac
index a4f20725e..5a0339f1c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -16,7 +16,7 @@
 # problem to the user.
 AC_PREREQ([2.59])
 
-m4_define([ngspice_major_version], [37])
+m4_define([ngspice_major_version], [37+])
 m4_define([ngspice_minor_version], [0])
 m4_define([ngspice_version],
       [ngspice_major_version])
diff --git a/src/include/ngspice/sharedspice.h b/src/include/ngspice/sharedspice.h
index 28bd5fd3e..d133e3ef5 100644
--- a/src/include/ngspice/sharedspice.h
+++ b/src/include/ngspice/sharedspice.h
@@ -92,7 +92,7 @@ are of type bool if sharedspice.h is used externally.
 */
 
 #ifndef NGSPICE_PACKAGE_VERSION
-#define NGSPICE_PACKAGE_VERSION "37"
+#define NGSPICE_PACKAGE_VERSION "37+"
 #endif
 /* we have NG_BOOL instead of BOOL */
 #ifndef HAS_NG_BOOL
diff --git a/visualc/src/include/ngspice/config.h b/visualc/src/include/ngspice/config.h
index adf298e1e..c332432b9 100644
--- a/visualc/src/include/ngspice/config.h
+++ b/visualc/src/include/ngspice/config.h
@@ -15,7 +15,7 @@
 #define PACKAGE "ngspice"
 
 /* Version number of package */
-#define VERSION "37"
+#define VERSION "37+"
 
 /* Define the directory for executables */
 #define NGSPICEBINDIR "../bin"