diff --git a/core/model/src/main/kotlin/au/com/dius/pact/core/model/ContentType.kt b/core/model/src/main/kotlin/au/com/dius/pact/core/model/ContentType.kt
index b5af1903e1..ec26829bf6 100644
--- a/core/model/src/main/kotlin/au/com/dius/pact/core/model/ContentType.kt
+++ b/core/model/src/main/kotlin/au/com/dius/pact/core/model/ContentType.kt
@@ -48,7 +48,7 @@ class ContentType(val contentType: MediaType?) {
 
   fun isBinaryType(): Boolean {
     return if (contentType != null) {
-      val superType = registry.getSupertype(contentType)
+      val superType = registry.getSupertype(contentType) ?: MediaType.OCTET_STREAM
       val type = contentType.type
       val baseType = superType.type
       val override = System.getProperty("pact.content_type.override.$type.${contentType.subtype}")
diff --git a/core/model/src/test/groovy/au/com/dius/pact/core/model/ContentTypeSpec.groovy b/core/model/src/test/groovy/au/com/dius/pact/core/model/ContentTypeSpec.groovy
index ba0d3dc66a..73f382b3d6 100644
--- a/core/model/src/test/groovy/au/com/dius/pact/core/model/ContentTypeSpec.groovy
+++ b/core/model/src/test/groovy/au/com/dius/pact/core/model/ContentTypeSpec.groovy
@@ -67,21 +67,22 @@ class ContentTypeSpec extends Specification {
 
     where:
 
-    value                  || result
-    ''                     || false
-    'text/plain'           || false
-    'application/pdf'      || true
-    'application/zip'      || true
-    'application/json'     || false
-    'application/hal+json' || false
-    'application/HAL+JSON' || false
-    'application/xml'      || false
-    'application/atom+xml' || false
-    'image/jpeg'           || true
-    'video/H264'           || true
-    'audio/aac'            || true
-    'text/csv'             || false
-    'multipart/form-data'  || true
+    value                      || result
+    ''                         || false
+    'text/plain'               || false
+    'application/pdf'          || true
+    'application/zip'          || true
+    'application/json'         || false
+    'application/hal+json'     || false
+    'application/HAL+JSON'     || false
+    'application/xml'          || false
+    'application/atom+xml'     || false
+    'application/octet-stream' || true
+    'image/jpeg'               || true
+    'video/H264'               || true
+    'audio/aac'                || true
+    'text/csv'                 || false
+    'multipart/form-data'      || true
 
     contentType = new ContentType(value)
   }