diff --git a/CMakeLists.txt b/CMakeLists.txt
index 99fcc5df7..957c589d3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -65,6 +65,11 @@ project(CALAMARES VERSION ${CALAMARES_VERSION_SHORT} LANGUAGES C CXX HOMEPAGE_UR
 if(NOT CALAMARES_RELEASE_MODE AND CMAKE_SOURCE_DIR STREQUAL CMAKE_BINARY_DIR)
     message(FATAL_ERROR "Do not build development versions in the source-directory.")
 endif()
+# Calamares in the 3.3 series promises ABI compatbility, so it sets a
+# .so-version equal to the series number. We use ci/abicheck.sh to
+# keep track of this. Note that the **alpha** releases also have
+# such an .so-version, but are not ABI-stable yet.
+set(CALAMARES_SOVERSION "${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}")
 
 ### OPTIONS
 #
diff --git a/src/libcalamares/CMakeLists.txt b/src/libcalamares/CMakeLists.txt
index 1506f4791..767c2ab39 100644
--- a/src/libcalamares/CMakeLists.txt
+++ b/src/libcalamares/CMakeLists.txt
@@ -97,7 +97,7 @@ set_target_properties(
     calamares
     PROPERTIES
         VERSION ${CALAMARES_VERSION_SHORT}
-        SOVERSION ${CALAMARES_VERSION_SHORT}
+        SOVERSION ${CALAMARES_SOVERSION}
         INTERFACE_INCLUDE_DIRECTORIES ${CMAKE_INSTALL_FULL_INCLUDEDIR}/libcalamares
 )
 target_link_libraries(calamares LINK_PUBLIC yamlcpp::yamlcpp Qt5::Core KF5::CoreAddons)
diff --git a/src/libcalamaresui/CMakeLists.txt b/src/libcalamaresui/CMakeLists.txt
index 406bd3ce4..20af93a56 100644
--- a/src/libcalamaresui/CMakeLists.txt
+++ b/src/libcalamaresui/CMakeLists.txt
@@ -53,6 +53,7 @@ calamares_add_library(calamaresui
     UI
         utils/ErrorDialog/ErrorDialog.ui
     VERSION ${CALAMARES_VERSION_SHORT}
+    SOVERSION ${CALAMARES_SOVERSION}
 )
 target_link_libraries(calamaresui PRIVATE yamlcpp::yamlcpp)
 if(KF5CoreAddons_FOUND AND KF5CoreAddons_VERSION VERSION_GREATER_EQUAL 5.58)