diff --git a/base/numericalDerivative.h b/base/numericalDerivative.h
index e7f74b70e..be64c672b 100644
--- a/base/numericalDerivative.h
+++ b/base/numericalDerivative.h
@@ -43,8 +43,8 @@ namespace gtsam {
 
 
 	/** global functions for converting to a LieVector for use with numericalDerivative */
-	LieVector makeLieVector(const Vector& v) { return LieVector(v); }
-	LieVector makeLieVectorD(double d) { return LieVector(Vector_(1, d)); }
+        inline LieVector makeLieVector(const Vector& v) { return LieVector(v); }
+	inline LieVector makeLieVectorD(double d) { return LieVector(Vector_(1, d)); }
 
 	/**
 	 * Numerically compute gradient of scalar function