diff --git a/dockerfiles/Dockerfile b/dockerfiles/Dockerfile
index 9e96c846991..7c4c5ce940a 100644
--- a/dockerfiles/Dockerfile
+++ b/dockerfiles/Dockerfile
@@ -49,6 +49,7 @@ RUN apt-get update && \
     pkg-config \
     libsystemd-dev \
     zlib1g-dev \
+    libzstd-dev \
     libpq-dev \
     postgresql-server-dev-all \
     flex \
@@ -263,7 +264,7 @@ RUN apt-get update && \
     openssl \
     htop atop strace iotop sysstat ncdu logrotate hdparm pciutils psmisc tree pv \
     make tar flex bison \
-    libssl-dev libsasl2-dev libsystemd-dev zlib1g-dev libpq-dev libyaml-dev postgresql-server-dev-all \
+    libssl-dev libsasl2-dev libsystemd-dev zlib1g-dev libzstd-dev libpq-dev libyaml-dev postgresql-server-dev-all \
     && apt-get satisfy -y cmake "cmake (<< 4.0)" \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/*
diff --git a/tests/runtime/CMakeLists.txt b/tests/runtime/CMakeLists.txt
index 104750b456e..1e5d4b7d571 100644
--- a/tests/runtime/CMakeLists.txt
+++ b/tests/runtime/CMakeLists.txt
@@ -345,6 +345,17 @@ foreach(source_file ${CHECK_PROGRAMS})
   endif()
 endforeach()
 
+# The out_kafka runtime test includes librdkafka's public header directly, so it
+# needs the same include path the in_kafka/out_kafka plugins use. Cover both the
+# system librdkafka (pkg-config) and the bundled librdkafka build.
+if(TARGET flb-rt-out_kafka)
+  if(DEFINED KAFKA_INCLUDEDIR)
+    target_include_directories(flb-rt-out_kafka PRIVATE ${KAFKA_INCLUDEDIR}/librdkafka)
+  endif()
+  target_include_directories(flb-rt-out_kafka PRIVATE
+    ${FLB_PATH_ROOT_SOURCE}/${FLB_PATH_LIB_RDKAFKA}/src)
+endif()
+
 function(flb_runtime_lock_tests resource_name)
   foreach(test_name ${ARGN})
     if (TEST ${test_name})
diff --git a/tests/runtime/out_kafka.c b/tests/runtime/out_kafka.c
index 4c5c852bc44..d18ff7f5643 100644
--- a/tests/runtime/out_kafka.c
+++ b/tests/runtime/out_kafka.c
@@ -3,9 +3,34 @@
 #include <fluent-bit.h>
 #include "flb_tests_runtime.h"
 
+#include "rdkafka.h"
+
 /* Test data */
 #include "data/td/json_td.h"
 
+/*
+ * Ensure librdkafka was compiled with zstd support so Kafka producers can
+ * negotiate zstd compression. Setting compression.codec to zstd only succeeds
+ * when WITH_ZSTD was enabled at build time, otherwise rd_kafka_conf_set
+ * reports the codec as not built in.
+ */
+void flb_test_zstd_compression_available()
+{
+    rd_kafka_conf_t *conf;
+    rd_kafka_conf_res_t res;
+    char errstr[512] = {0};
+
+    conf = rd_kafka_conf_new();
+    TEST_CHECK(conf != NULL);
+
+    res = rd_kafka_conf_set(conf, "compression.codec", "zstd",
+                            errstr, sizeof(errstr));
+    TEST_CHECK(res == RD_KAFKA_CONF_OK);
+    TEST_MSG("compression.codec=zstd rejected: %s", errstr);
+
+    rd_kafka_conf_destroy(conf);
+}
+
 
 void flb_test_raw_format()
 {
@@ -44,6 +69,7 @@ void flb_test_raw_format()
 }
 
 TEST_LIST = {
+  { "zstd_compression_available", flb_test_zstd_compression_available },
   { "raw_format", flb_test_raw_format },
   { NULL, NULL },
 };