2 files changed, 19 insertions, 2 deletions
diff --git a/src/main/java/org/zwobble/mammoth/internal/docx/ContentTypes.java b/src/main/java/org/zwobble/mammoth/internal/docx/ContentTypes.java
index b8c6817..e778f73 100644
--- a/src/main/java/org/zwobble/mammoth/internal/docx/ContentTypes.java
+++ b/src/main/java/org/zwobble/mammoth/internal/docx/ContentTypes.java
@@ -1,7 +1,7 @@
 package org.zwobble.mammoth.internal.docx;
 
-import com.google.common.collect.ImmutableMap;
 import com.google.common.io.Files;
+import org.zwobble.mammoth.internal.util.MammothMaps;
 
 import java.util.Map;
 import java.util.Optional;
@@ -12,7 +12,7 @@ import static org.zwobble.mammoth.internal.util.MammothMaps.map;
 public class ContentTypes {
     public static final ContentTypes DEFAULT = new ContentTypes(map(), map());
 
-    private static final Map<String, String> imageExtensions = ImmutableMap.<String, String>builder()
+    private static final Map<String, String> imageExtensions = MammothMaps.<String, String>builder()
         .put("png", "png")
         .put("gif", "gif")
         .put("jpeg", "jpeg")
diff --git a/src/main/java/org/zwobble/mammoth/internal/util/MammothMaps.java b/src/main/java/org/zwobble/mammoth/internal/util/MammothMaps.java
index 1d8780c..d3ba8c5 100644
--- a/src/main/java/org/zwobble/mammoth/internal/util/MammothMaps.java
+++ b/src/main/java/org/zwobble/mammoth/internal/util/MammothMaps.java
@@ -77,4 +77,21 @@ public class MammothMaps {
         }
         return result;
     }
+
+    public static <K, V> Builder<K, V> builder() {
+        return new Builder<>();
+    }
+
+    public static class Builder<K, V> {
+        private final Map<K, V> values = new HashMap<>();
+
+        public Builder<K, V> put(K key, V value) {
+            values.put(key, value);
+            return this;
+        }
+
+        public Map<K, V> build() {
+            return values;
+        }
+    }
 }