diff --git a/src/main/java/com/github/stephengold/joltjni/BodyCreationSettings.java b/src/main/java/com/github/stephengold/joltjni/BodyCreationSettings.java
index 793db7bb..c71a0d34 100644
--- a/src/main/java/com/github/stephengold/joltjni/BodyCreationSettings.java
+++ b/src/main/java/com/github/stephengold/joltjni/BodyCreationSettings.java
@@ -39,8 +39,8 @@ public class BodyCreationSettings extends JoltPhysicsObject {
      * @param motionType the desired motion type (not null)
      * @param objLayer the ID of the desired object layer
      */
-    public BodyCreationSettings(Shape shape,
-            RVec3Arg loc, Quat orient, EMotionType motionType, int objLayer) {
+    public BodyCreationSettings(Shape shape, RVec3Arg loc, QuatArg orient,
+            EMotionType motionType, int objLayer) {
         long shapeVa = shape.va();
         int motionTypeOrdinal = motionType.ordinal();
         long bodySettingsVa = createBodyCreationSettingsFromShape(
@@ -59,8 +59,8 @@ public BodyCreationSettings(Shape shape,
      * @param motionType the desired motion type (not null)
      * @param objLayer the ID of the desired object layer
      */
-    public BodyCreationSettings(ShapeSettings shapeSettings,
-            RVec3Arg loc, Quat orient, EMotionType motionType, int objLayer) {
+    public BodyCreationSettings(ShapeSettings shapeSettings, RVec3Arg loc,
+            QuatArg orient, EMotionType motionType, int objLayer) {
         long shapeSettingsVa = shapeSettings.va();
         int motionTypeOrdinal = motionType.ordinal();
         long bodySettingsVa = createBodyCreationSettingsFromShapeSettings(
diff --git a/src/main/java/com/github/stephengold/joltjni/Quat.java b/src/main/java/com/github/stephengold/joltjni/Quat.java
index 776029b6..7203e0a3 100644
--- a/src/main/java/com/github/stephengold/joltjni/Quat.java
+++ b/src/main/java/com/github/stephengold/joltjni/Quat.java
@@ -31,7 +31,7 @@ of this software and associated documentation files (the "Software"), to deal
  *
  * @author Stephen Gold sgold@sonic.net
  */
-final public class Quat {
+final public class Quat implements QuatArg {
     // *************************************************************************
     // fields
 
@@ -95,6 +95,8 @@ public void set(float x, float y, float z, float w) {
         this.z = z;
         this.w = w;
     }
+    // *************************************************************************
+    // QuatArg methods
 
     /**
      * Return the real (W) component in single precision. The quaternion is
@@ -102,6 +104,7 @@ public void set(float x, float y, float z, float w) {
      *
      * @return the component value
      */
+    @Override
     public float getW() {
         return w;
     }
@@ -112,6 +115,7 @@ public float getW() {
      *
      * @return the component value
      */
+    @Override
     public float getX() {
         return x;
     }
@@ -122,6 +126,7 @@ public float getX() {
      *
      * @return the component value
      */
+    @Override
     public float getY() {
         return y;
     }
@@ -132,6 +137,7 @@ public float getY() {
      *
      * @return the component value
      */
+    @Override
     public float getZ() {
         return z;
     }
diff --git a/src/main/java/com/github/stephengold/joltjni/QuatArg.java b/src/main/java/com/github/stephengold/joltjni/QuatArg.java
new file mode 100644
index 00000000..1f66846b
--- /dev/null
+++ b/src/main/java/com/github/stephengold/joltjni/QuatArg.java
@@ -0,0 +1,64 @@
+/*
+Copyright (c) 2024 Stephen Gold
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+ */
+package com.github.stephengold.joltjni;
+
+/**
+ * A read-only interface to {@code Quat} instances.
+ *
+ * @author Stephen Gold sgold@sonic.net
+ */
+public interface QuatArg {
+    // *************************************************************************
+    // new methods exposed
+
+    /**
+     * Return the real (W) component in single precision. The quaternion is
+     * unaffected.
+     *
+     * @return the component value
+     */
+    float getW();
+
+    /**
+     * Return the first imaginary (X) component in single precision. The
+     * quaternion is unaffected.
+     *
+     * @return the component value
+     */
+    float getX();
+
+    /**
+     * Return the 2nd imaginary (Y) component in single precision. The
+     * quaternion is unaffected.
+     *
+     * @return the component value
+     */
+    float getY();
+
+    /**
+     * Return the 3rd imaginary (Z) component in single precision. The
+     * quaternion is unaffected.
+     *
+     * @return the component value
+     */
+    float getZ();
+}