diff --git a/CMakeLists.txt b/CMakeLists.txt
index dbfa9a1..441889b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,7 @@
 
 project(nanopb C)
 
-set(nanopb_VERSION_STRING nanopb-0.4.1)
+set(nanopb_VERSION_STRING nanopb-0.4.2-dev)
 set(nanopb_SOVERSION 0)
 
 string(REPLACE "nanopb-" "" nanopb_VERSION ${nanopb_VERSION_STRING})
diff --git a/conanfile.py b/conanfile.py
index c2bfb93..8283261 100644
--- a/conanfile.py
+++ b/conanfile.py
@@ -3,7 +3,7 @@
 
 class NanoPbConan(ConanFile):
     name = "nanopb"
-    version = "0.4.1"
+    version = "0.4.2-dev"
     license = "zlib"
     url = "https://jpa.kapsi.fi/nanopb/"
     description = "Protocol Buffers with small code size"
diff --git a/extra/poetry/pyproject.toml b/extra/poetry/pyproject.toml
index a312787..2841ec2 100644
--- a/extra/poetry/pyproject.toml
+++ b/extra/poetry/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "nanopb"
-version = "0.4.1"
+version = "0.4.2-dev"
 description = "Nanopb is a small code-size Protocol Buffers implementation in ansi C. It is especially suitable for use in microcontrollers, but fits any memory restricted system."
 authors = ["Petteri Aimonen <jpa@npb.mail.kapsi.fi>"]
 license = "Zlib"
diff --git a/generator/nanopb_generator.py b/generator/nanopb_generator.py
index 274988c..43e5eaf 100755
--- a/generator/nanopb_generator.py
+++ b/generator/nanopb_generator.py
@@ -4,7 +4,7 @@
 from __future__ import unicode_literals
 
 '''Generate header file for nanopb from a ProtoBuf FileDescriptorSet.'''
-nanopb_version = "nanopb-0.4.1"
+nanopb_version = "nanopb-0.4.2-dev"
 
 import sys
 import re
diff --git a/pb.h b/pb.h
index 8e87b62..09c2526 100644
--- a/pb.h
+++ b/pb.h
@@ -55,7 +55,7 @@
 
 /* Version of the nanopb library. Just in case you want to check it in
  * your own program. */
-#define NANOPB_VERSION nanopb-0.4.1
+#define NANOPB_VERSION nanopb-0.4.2-dev
 
 /* Include all the system headers needed by nanopb. You will need the
  * definitions of the following: