diff --git a/docker/images/proxysql/deb-compliant/entrypoint/entrypoint.bash b/docker/images/proxysql/deb-compliant/entrypoint/entrypoint.bash
index 4d8329e3c..3cde22c0a 100755
--- a/docker/images/proxysql/deb-compliant/entrypoint/entrypoint.bash
+++ b/docker/images/proxysql/deb-compliant/entrypoint/entrypoint.bash
@@ -41,6 +41,22 @@ else
 	build_target="$PROXYSQL_BUILD_TYPE"
 fi
 
+# When PROXYSQLGENAI=1 is set, the build recurses into plugins/mysqlx/
+# which dynamically links against the system libprotobuf (3.x). Some of
+# the v4.0.0 packaging images were built before plugins/mysqlx existed
+# and do not yet ship libprotobuf-dev. Install it on demand here so the
+# plugin's pkg-config check at plugins/mysqlx/Makefile:47 succeeds. The
+# install is idempotent — apt-get returns 0 if the package is already
+# present. Skip silently for v3.x builds where PROXYSQLGENAI is unset
+# and the plugin path is not exercised.
+if [[ "${PROXYSQLGENAI:-}" == "1" ]]; then
+    if ! pkg-config --exists protobuf 2>/dev/null; then
+        echo "==> Installing libprotobuf-dev (required for PROXYSQLGENAI=1 mysqlx plugin build)"
+        apt-get update -qq
+        apt-get install -y --no-install-recommends libprotobuf-dev
+    fi
+fi
+
 # clean is expensive, do it before, outside of container
 #${MAKE} cleanbuild
 if [[ "${PROXYSQLGENAI:-}" == "1" ]]; then
diff --git a/docker/images/proxysql/rhel-compliant/entrypoint/entrypoint.bash b/docker/images/proxysql/rhel-compliant/entrypoint/entrypoint.bash
index 88d33e304..a6997070f 100755
--- a/docker/images/proxysql/rhel-compliant/entrypoint/entrypoint.bash
+++ b/docker/images/proxysql/rhel-compliant/entrypoint/entrypoint.bash
@@ -41,6 +41,25 @@ else
 	build_target="$PROXYSQL_BUILD_TYPE"
 fi
 
+# See deb-compliant entrypoint for the rationale: PROXYSQLGENAI=1
+# triggers a build of plugins/mysqlx/ which dynamically links against
+# the system libprotobuf (3.x). Some of the v4.0.0 packaging images
+# were built before plugins/mysqlx existed and do not yet ship
+# protobuf-devel. Install it on demand for RHEL-family images.
+if [[ "${PROXYSQLGENAI:-}" == "1" ]]; then
+    if ! pkg-config --exists protobuf 2>/dev/null; then
+        echo "==> Installing protobuf-devel (required for PROXYSQLGENAI=1 mysqlx plugin build)"
+        if command -v dnf >/dev/null 2>&1; then
+            dnf install -y protobuf-devel
+        elif command -v yum >/dev/null 2>&1; then
+            yum install -y protobuf-devel
+        else
+            echo "ERROR: cannot install protobuf-devel (neither dnf nor yum present)" >&2
+            exit 1
+        fi
+    fi
+fi
+
 # clean is expensive, do it before, outside of container
 #${MAKE} cleanbuild
 if [[ "${PROXYSQLGENAI:-}" == "1" ]]; then
diff --git a/docker/images/proxysql/suse-compliant/entrypoint/entrypoint.bash b/docker/images/proxysql/suse-compliant/entrypoint/entrypoint.bash
index 2eff69862..1b1e97d1f 100755
--- a/docker/images/proxysql/suse-compliant/entrypoint/entrypoint.bash
+++ b/docker/images/proxysql/suse-compliant/entrypoint/entrypoint.bash
@@ -41,6 +41,23 @@ else
 	build_target="$PROXYSQL_BUILD_TYPE"
 fi
 
+# See deb-compliant entrypoint for the rationale: PROXYSQLGENAI=1
+# triggers a build of plugins/mysqlx/ which dynamically links against
+# the system libprotobuf (3.x). Some of the v4.0.0 packaging images
+# were built before plugins/mysqlx existed and do not yet ship
+# protobuf-devel. Install it on demand for SUSE-family images.
+if [[ "${PROXYSQLGENAI:-}" == "1" ]]; then
+    if ! pkg-config --exists protobuf 2>/dev/null; then
+        echo "==> Installing protobuf-devel (required for PROXYSQLGENAI=1 mysqlx plugin build)"
+        if command -v zypper >/dev/null 2>&1; then
+            zypper install -y libprotobuf-c-devel || zypper install -y protobuf-devel
+        else
+            echo "ERROR: cannot install protobuf-devel (zypper not present)" >&2
+            exit 1
+        fi
+    fi
+fi
+
 # clean is expensive, do it before, outside of container
 #${MAKE} cleanbuild
 if [[ "${PROXYSQLGENAI:-}" == "1" ]]; then