diff --git a/ksql-api/src/main/java/io/confluent/ksql/api/server/ApiServerConfig.java b/ksql-api/src/main/java/io/confluent/ksql/api/server/ApiServerConfig.java
index 38a195b0ac0a..754e68259f61 100644
--- a/ksql-api/src/main/java/io/confluent/ksql/api/server/ApiServerConfig.java
+++ b/ksql-api/src/main/java/io/confluent/ksql/api/server/ApiServerConfig.java
@@ -15,12 +15,16 @@
 
 package io.confluent.ksql.api.server;
 
-import io.confluent.common.config.AbstractConfig;
-import io.confluent.common.config.ConfigDef;
-import io.confluent.common.config.ConfigDef.Importance;
-import io.confluent.common.config.ConfigDef.Type;
+import static io.confluent.ksql.configdef.ConfigValidators.zeroOrPositive;
+
 import io.confluent.ksql.util.KsqlConfig;
 import java.util.Map;
+import org.apache.kafka.common.config.AbstractConfig;
+import org.apache.kafka.common.config.ConfigDef;
+import org.apache.kafka.common.config.ConfigDef.Importance;
+import org.apache.kafka.common.config.ConfigDef.Type;
+import org.apache.kafka.common.config.ConfigDef.Validator;
+import org.apache.kafka.common.config.ConfigException;
 
 /**
  * Config for the API server
@@ -91,6 +95,7 @@ private static String propertyName(final String name) {
           VERTICLE_INSTANCES,
           Type.INT,
           DEFAULT_VERTICLE_INSTANCES,
+          oneOrMore(),
           Importance.MEDIUM,
           VERTICLE_INSTANCES_DOC)
       .define(
@@ -103,6 +108,7 @@ private static String propertyName(final String name) {
           LISTEN_PORT,
           Type.INT,
           DEFAULT_LISTEN_PORT,
+          zeroOrPositive(),
           Importance.MEDIUM,
           LISTEN_PORT_DOC)
       .define(
@@ -145,12 +151,14 @@ private static String propertyName(final String name) {
           WORKER_POOL_SIZE,
           Type.INT,
           DEFAULT_WORKER_POOL_SIZE,
+          zeroOrPositive(),
           Importance.MEDIUM,
           WORKER_POOL_DOC)
       .define(
           MAX_PUSH_QUERIES,
           Type.INT,
           DEFAULT_MAX_PUSH_QUERIES,
+          zeroOrPositive(),
           Importance.MEDIUM,
           MAX_PUSH_QUERIES_DOC);
 
@@ -158,4 +166,20 @@ public ApiServerConfig(final Map<?, ?> map) {
     super(CONFIG_DEF, map);
   }
 
+  private static Validator oneOrMore() {
+    return (name, val) -> {
+      if (val instanceof Long) {
+        if (((Long) val) < 1) {
+          throw new ConfigException(name, val, "Not >= 1");
+        }
+      } else if (val instanceof Integer) {
+        if (((Integer) val) < 1) {
+          throw new ConfigException(name, val, "Not >= 1");
+        }
+      } else {
+        throw new IllegalArgumentException("validator should only be used with int, long");
+      }
+    };
+  }
+
 }