diff --git a/java/org/apache/el/parser/AstFunction.java b/java/org/apache/el/parser/AstFunction.java
index 2621d42c2bf0..edac458c2059 100644
--- a/java/org/apache/el/parser/AstFunction.java
+++ b/java/org/apache/el/parser/AstFunction.java
@@ -170,9 +170,16 @@ public Object getValue(EvaluationContext ctx) throws ELException {
                             // Java semantics: an empty array is passed when no
                             // varargs elements are supplied
                             params[i] = new Object[0];
-                        } else if (inputParameterCount == methodParameterCount &&
-                                isArray(parameters.jjtGetChild(i).getValue(ctx))) {
-                            params[i] = parameters.jjtGetChild(i).getValue(ctx);
+                        } else if (inputParameterCount == methodParameterCount) {
+                            // Evaluate the single argument once: it is either
+                            // the varargs array itself or its only element
+                            Object value = parameters.jjtGetChild(i).getValue(ctx);
+                            if (isArray(value)) {
+                                params[i] = value;
+                            } else {
+                                params[i] = new Object[] { ELSupport.coerceToType(ctx, value,
+                                        paramTypes[i].getComponentType()) };
+                            }
                         } else {
                             Object[] varargs = new Object[inputParameterCount - methodParameterCount + 1];
                             Class<?> target = paramTypes[i].getComponentType();
diff --git a/test/org/apache/el/parser/TestAstFunction.java b/test/org/apache/el/parser/TestAstFunction.java
index 2137afe56513..7604c891445d 100644
--- a/test/org/apache/el/parser/TestAstFunction.java
+++ b/test/org/apache/el/parser/TestAstFunction.java
@@ -25,6 +25,7 @@
 import org.junit.Assert;
 import org.junit.Test;
 
+import org.apache.el.TesterBeanK;
 import org.apache.el.TesterFunctions;
 
 public class TestAstFunction {
@@ -108,6 +109,19 @@ public void testVarargMethod() throws NoSuchMethodException, SecurityException {
         Assert.assertEquals("one", result);
     }
 
+    @Test
+    public void testVarargMethodSingleArgumentEvaluatedOnce() throws NoSuchMethodException {
+        // The argument that alone fills the varargs parameter must be evaluated
+        // exactly once, as each argument is when there are several
+        ELProcessor processor = new ELProcessor();
+        TesterBeanK bean = new TesterBeanK();
+        processor.defineBean("beanK", bean);
+        processor.defineFunction("fn", "format", String.class.getMethod("format", String.class, Object[].class));
+
+        Assert.assertEquals("1", processor.getValue("fn:format('%s', beanK.next())", String.class));
+        Assert.assertEquals(1, bean.argCalls);
+    }
+
     @Test
     public void testVarargMethodEmptyVarargs01() throws NoSuchMethodException {
         // Java passes an empty array, never null, to a varargs method that is