diff --git a/impl/src/main/java/io/jsonwebtoken/impl/io/RuntimeClasspathDeserializerLocator.java b/impl/src/main/java/io/jsonwebtoken/impl/io/RuntimeClasspathDeserializerLocator.java
index 61d2dac7..034fe34e 100644
--- a/impl/src/main/java/io/jsonwebtoken/impl/io/RuntimeClasspathDeserializerLocator.java
+++ b/impl/src/main/java/io/jsonwebtoken/impl/io/RuntimeClasspathDeserializerLocator.java
@@ -30,9 +30,9 @@ public class RuntimeClasspathDeserializerLocator<T> implements InstanceLocator<D
 
     @SuppressWarnings("WeakerAccess") //to allow testing override
     protected Deserializer<T> locate() {
-        if (isAvailable("com.fasterxml.jackson.databind.ObjectMapper")) {
+        if (isAvailable("io.jsonwebtoken.io.JacksonDeserializer")) {
             return Classes.newInstance("io.jsonwebtoken.io.JacksonDeserializer");
-        } else if (isAvailable("org.json.JSONObject")) {
+        } else if (isAvailable("io.jsonwebtoken.io.OrgJsonDeserializer")) {
             return Classes.newInstance("io.jsonwebtoken.io.OrgJsonDeserializer");
         } else {
             throw new IllegalStateException("Unable to discover any JSON Deserializer implementations on the classpath.");
diff --git a/impl/src/main/java/io/jsonwebtoken/impl/io/RuntimeClasspathSerializerLocator.java b/impl/src/main/java/io/jsonwebtoken/impl/io/RuntimeClasspathSerializerLocator.java
index 63a6137d..c2efbfd1 100644
--- a/impl/src/main/java/io/jsonwebtoken/impl/io/RuntimeClasspathSerializerLocator.java
+++ b/impl/src/main/java/io/jsonwebtoken/impl/io/RuntimeClasspathSerializerLocator.java
@@ -30,9 +30,9 @@ public class RuntimeClasspathSerializerLocator implements InstanceLocator<Serial
 
     @SuppressWarnings("WeakerAccess") //to allow testing override
     protected Serializer<Object> locate() {
-        if (isAvailable("com.fasterxml.jackson.databind.ObjectMapper")) {
+        if (isAvailable("io.jsonwebtoken.io.JacksonSerializer")) {
             return Classes.newInstance("io.jsonwebtoken.io.JacksonSerializer");
-        } else if (isAvailable("org.json.JSONObject")) {
+        } else if (isAvailable("io.jsonwebtoken.io.OrgJsonSerializer")) {
             return Classes.newInstance("io.jsonwebtoken.io.OrgJsonSerializer");
         } else {
             throw new IllegalStateException("Unable to discover any JSON Serializer implementations on the classpath.");
diff --git a/impl/src/test/groovy/io/jsonwebtoken/impl/io/RuntimeClasspathDeserializerLocatorTest.groovy b/impl/src/test/groovy/io/jsonwebtoken/impl/io/RuntimeClasspathDeserializerLocatorTest.groovy
index 22756feb..7013aa2a 100644
--- a/impl/src/test/groovy/io/jsonwebtoken/impl/io/RuntimeClasspathDeserializerLocatorTest.groovy
+++ b/impl/src/test/groovy/io/jsonwebtoken/impl/io/RuntimeClasspathDeserializerLocatorTest.groovy
@@ -86,7 +86,7 @@ class RuntimeClasspathDeserializerLocatorTest {
         def locator = new RuntimeClasspathDeserializerLocator() {
             @Override
             protected boolean isAvailable(String fqcn) {
-                if (ObjectMapper.class.getName().equals(fqcn)) {
+                if (JacksonDeserializer.class.getName().equals(fqcn)) {
                     return false; //skip it to allow the OrgJson impl to be created
                 }
                 return super.isAvailable(fqcn)
diff --git a/impl/src/test/groovy/io/jsonwebtoken/impl/io/RuntimeClasspathSerializerLocatorTest.groovy b/impl/src/test/groovy/io/jsonwebtoken/impl/io/RuntimeClasspathSerializerLocatorTest.groovy
index 2e6c2aef..96daae90 100644
--- a/impl/src/test/groovy/io/jsonwebtoken/impl/io/RuntimeClasspathSerializerLocatorTest.groovy
+++ b/impl/src/test/groovy/io/jsonwebtoken/impl/io/RuntimeClasspathSerializerLocatorTest.groovy
@@ -1,6 +1,5 @@
 package io.jsonwebtoken.impl.io
 
-import com.fasterxml.jackson.databind.ObjectMapper
 import io.jsonwebtoken.io.Serializer
 import io.jsonwebtoken.io.JacksonSerializer
 import io.jsonwebtoken.io.OrgJsonSerializer
@@ -86,7 +85,7 @@ class RuntimeClasspathSerializerLocatorTest {
         def locator = new RuntimeClasspathSerializerLocator() {
             @Override
             protected boolean isAvailable(String fqcn) {
-                if (ObjectMapper.class.getName().equals(fqcn)) {
+                if (JacksonSerializer.class.getName().equals(fqcn)) {
                     return false //skip it to allow the OrgJson impl to be created
                 }
                 return super.isAvailable(fqcn)