diff --git a/src/runtime/java/jpgf.c b/src/runtime/java/jpgf.c
index 5622b4885..fd7fe337d 100644
--- a/src/runtime/java/jpgf.c
+++ b/src/runtime/java/jpgf.c
@@ -1575,6 +1575,13 @@ Java_org_grammaticalframework_pgf_Expr_hashCode(JNIEnv* env, jobject self)
 	return pgf_expr_hash(0, e);
 }
 
+JNIEXPORT jint JNICALL
+Java_org_grammaticalframework_pgf_Expr_size(JNIEnv* env, jobject self)
+{
+	PgfExpr e = gu_variant_from_ptr(l2p(get_ref(env, self)));
+	return pgf_expr_size(e);
+}
+
 JNIEXPORT jstring JNICALL
 Java_org_grammaticalframework_pgf_Type_getCategory(JNIEnv* env, jobject self)
 {
diff --git a/src/runtime/java/org/grammaticalframework/pgf/Expr.java b/src/runtime/java/org/grammaticalframework/pgf/Expr.java
index 40655cbcb..db0876bf8 100644
--- a/src/runtime/java/org/grammaticalframework/pgf/Expr.java
+++ b/src/runtime/java/org/grammaticalframework/pgf/Expr.java
@@ -108,6 +108,9 @@ public class Expr implements Serializable {
 			return showExpr(ref);
 		}
 
+		/** Computes the number of functions in the expression */
+		public native int size();
+
 		/** Reads a string in the GF syntax for abstract expressions
 		 * and returns an object representing the expression. */
 		public static native Expr readExpr(String s) throws PGFError;