diff --git a/doc/doxygen/lwip.Doxyfile b/doc/doxygen/lwip.Doxyfile
index 4b4d2ec5..d51fe67e 100644
--- a/doc/doxygen/lwip.Doxyfile
+++ b/doc/doxygen/lwip.Doxyfile
@@ -38,7 +38,7 @@ PROJECT_NAME           = "lwIP"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = "2.2.0"
+PROJECT_NUMBER         = "2.2.1.dev"
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
diff --git a/src/Filelists.cmake b/src/Filelists.cmake
index 3a0430e4..8008a440 100644
--- a/src/Filelists.cmake
+++ b/src/Filelists.cmake
@@ -14,11 +14,11 @@ endif()
 
 set(LWIP_VERSION_MAJOR    "2")
 set(LWIP_VERSION_MINOR    "2")
-set(LWIP_VERSION_REVISION "0")
+set(LWIP_VERSION_REVISION "1")
 # LWIP_VERSION_RC is set to LWIP_RC_RELEASE for official releases
 # LWIP_VERSION_RC is set to LWIP_RC_DEVELOPMENT for Git versions
 # Numbers 1..31 are reserved for release candidates
-set(LWIP_VERSION_RC       "LWIP_RC_RELEASE")
+set(LWIP_VERSION_RC       "LWIP_RC_DEVELOPMENT")
 
 if ("${LWIP_VERSION_RC}" STREQUAL "LWIP_RC_RELEASE")
     set(LWIP_VERSION_STRING
diff --git a/src/include/lwip/init.h b/src/include/lwip/init.h
index 43e5e04f..b10f7ec4 100644
--- a/src/include/lwip/init.h
+++ b/src/include/lwip/init.h
@@ -54,11 +54,11 @@ extern "C" {
 /** x.X.x: Minor version of the stack */
 #define LWIP_VERSION_MINOR      2
 /** x.x.X: Revision of the stack */
-#define LWIP_VERSION_REVISION   0
+#define LWIP_VERSION_REVISION   1
 /** For release candidates, this is set to 1..254
   * For official releases, this is set to 255 (LWIP_RC_RELEASE)
   * For development versions (Git), this is set to 0 (LWIP_RC_DEVELOPMENT) */
-#define LWIP_VERSION_RC         LWIP_RC_RELEASE
+#define LWIP_VERSION_RC         LWIP_RC_DEVELOPMENT
 
 /** LWIP_VERSION_RC is set to LWIP_RC_RELEASE for official releases */
 #define LWIP_RC_RELEASE         255