diff --git a/proton-c/soversion.cmake b/proton-c/soversion.cmake
index 4e7525e..bc60fdd 100644
--- a/proton-c/soversion.cmake
+++ b/proton-c/soversion.cmake
@@ -1,2 +1,2 @@
-set (PN_LIB_SOMAJOR 3)
+set (PN_LIB_SOMAJOR 4)
 set (PN_LIB_SOMINOR "0.0")