diff --git a/packages/proj/build.sh b/packages/proj/build.sh
index 99ec4ec9ab..886b65f17a 100644
--- a/packages/proj/build.sh
+++ b/packages/proj/build.sh
@@ -11,3 +11,15 @@ TERMUX_PKG_BREAKS="proj-dev"
 TERMUX_PKG_REPLACES="proj-dev"
 TERMUX_PKG_GROUPS="science"
 TERMUX_PKG_AUTO_UPDATE=true
+
+termux_step_post_get_source() {
+	# Do not forget to bump revision of reverse dependencies and rebuild them
+	# after SOVERSION is changed.
+	local _SOVERSION=25
+
+	local v=$(sed -En 's/^set\(PROJ_SOVERSION\s+([0-9]+).*/\1/p' \
+			CMakeLists.txt)
+	if [ "${v}" != "${_SOVERSION}" ]; then
+		termux_error_exit "SOVERSION guard check failed."
+	fi
+}