diff --git a/core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/util/Mimetype.java b/core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/util/Mimetype.java
index 887e21182aee..8c50fa7df290 100644
--- a/core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/util/Mimetype.java
+++ b/core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/util/Mimetype.java
@@ -116,10 +116,6 @@ public static Mimetype getInstance() {
      * to find the corresponding mime type. If the file has no extension, or the extension is not
      * available in the listing contained in this class, the default mimetype
      * <code>application/octet-stream</code> is returned.
-     * <p>
-     * A file extension is one or more characters that occur after the last period (.) in the file's name.
-     * If a file has no extension,
-     * Guesses the mimetype of file data based on the file's extension.
      *
      * @param path the file whose extension may match a known mimetype.
      * @return the file's mimetype based on its extension, or a default value of
@@ -132,7 +128,7 @@ public String getMimetype(Path path) {
         if (file != null) {
             return getMimetype(file.toString());
         }
-        return null;
+        return MIMETYPE_OCTET_STREAM;
     }
 
     /**
@@ -140,10 +136,6 @@ public String getMimetype(Path path) {
      * to find the corresponding mime type. If the file has no extension, or the extension is not
      * available in the listing contained in this class, the default mimetype
      * <code>application/octet-stream</code> is returned.
-     * <p>
-     * A file extension is one or more characters that occur after the last period (.) in the file's name.
-     * If a file has no extension,
-     * Guesses the mimetype of file data based on the file's extension.
      *
      * @param file the file whose extension may match a known mimetype.
      * @return the file's mimetype based on its extension, or a default value of
@@ -159,10 +151,6 @@ public String getMimetype(File file) {
      * no extension, or the extension is not available in the listing contained
      * in this class, the default mimetype <code>application/octet-stream</code>
      * is returned.
-     * <p>
-     * A file extension is one or more characters that occur after the last
-     * period (.) in the file's name. If a file has no extension, Guesses the
-     * mimetype of file data based on the file's extension.
      *
      * @param fileName The name of the file whose extension may match a known
      * mimetype.
diff --git a/core/sdk-core/src/test/java/software/amazon/awssdk/core/internal/util/MimetypeTest.java b/core/sdk-core/src/test/java/software/amazon/awssdk/core/internal/util/MimetypeTest.java
index 9f94d72e0032..a4dbd7df4611 100644
--- a/core/sdk-core/src/test/java/software/amazon/awssdk/core/internal/util/MimetypeTest.java
+++ b/core/sdk-core/src/test/java/software/amazon/awssdk/core/internal/util/MimetypeTest.java
@@ -16,7 +16,10 @@
 package software.amazon.awssdk.core.internal.util;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
 
+import java.nio.file.Path;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
@@ -48,4 +51,11 @@ public void unknownExtensions_defaulttoBeStream() throws Exception {
     public void noExtensions_defaulttoBeStream() throws Exception {
         assertThat(mimetype.getMimetype("test")).isEqualTo(Mimetype.MIMETYPE_OCTET_STREAM);
     }
+
+    @Test
+    public void pathWithoutFileName_defaulttoBeStream() throws Exception {
+        Path mockPath = mock(Path.class);
+        when(mockPath.getFileName()).thenReturn(null);
+        assertThat(mimetype.getMimetype(mockPath)).isEqualTo(Mimetype.MIMETYPE_OCTET_STREAM);
+    }
 }