diff --git a/plugins/org.eclipse.n4js.model/emf-gen/org/eclipse/n4js/n4JS/ArrowFunction.java b/plugins/org.eclipse.n4js.model/emf-gen/org/eclipse/n4js/n4JS/ArrowFunction.java
index 7a39167fa1..3ffb474761 100644
--- a/plugins/org.eclipse.n4js.model/emf-gen/org/eclipse/n4js/n4JS/ArrowFunction.java
+++ b/plugins/org.eclipse.n4js.model/emf-gen/org/eclipse/n4js/n4JS/ArrowFunction.java
@@ -96,6 +96,9 @@ public interface ArrowFunction extends FunctionExpression {
 	 * *
 	 * If {@link #isSingleExprImplicitReturn()} returns <code>true</code>, this method will return the single expression
 	 * that makes up the body of this arrow function, otherwise the behavior is undefined (might throw exception).
+	 * <p>
+	 * In case of broken AST, this method may return <code>null</code> even if {@link #isSingleExprImplicitReturn()}
+	 * returns <code>true</code>.
 	 * <!-- end-model-doc -->
 	 * @model kind="operation" unique="false"
 	 *        annotation="http://www.eclipse.org/emf/2002/GenModel body='&lt;%org.eclipse.n4js.n4JS.Statement%&gt; _head = &lt;%org.eclipse.xtext.xbase.lib.IterableExtensions%&gt;.&lt;&lt;%org.eclipse.n4js.n4JS.Statement%&gt;&gt;head(this.getBody().getStatements());\nreturn ((&lt;%org.eclipse.n4js.n4JS.ExpressionStatement%&gt;) _head).getExpression();'"
diff --git a/plugins/org.eclipse.n4js.model/model/N4JS.xcore b/plugins/org.eclipse.n4js.model/model/N4JS.xcore
index 282cdd868e..afeda61abf 100644
--- a/plugins/org.eclipse.n4js.model/model/N4JS.xcore
+++ b/plugins/org.eclipse.n4js.model/model/N4JS.xcore
@@ -619,6 +619,9 @@ class ArrowFunction extends FunctionExpression {
 	/**
 	 * If {@link #isSingleExprImplicitReturn()} returns <code>true</code>, this method will return the single expression
 	 * that makes up the body of this arrow function, otherwise the behavior is undefined (might throw exception).
+	 * <p>
+	 * In case of broken AST, this method may return <code>null</code> even if {@link #isSingleExprImplicitReturn()}
+	 * returns <code>true</code>.
 	 */
 	op Expression getSingleExpression() {
 		return (body.statements.head as ExpressionStatement).expression;
diff --git a/plugins/org.eclipse.n4js/src/org/eclipse/n4js/postprocessing/PolyProcessor_FunctionExpression.xtend b/plugins/org.eclipse.n4js/src/org/eclipse/n4js/postprocessing/PolyProcessor_FunctionExpression.xtend
index 423292f337..b249e4ad45 100644
--- a/plugins/org.eclipse.n4js/src/org/eclipse/n4js/postprocessing/PolyProcessor_FunctionExpression.xtend
+++ b/plugins/org.eclipse.n4js/src/org/eclipse/n4js/postprocessing/PolyProcessor_FunctionExpression.xtend
@@ -270,10 +270,12 @@ package class PolyProcessor_FunctionExpression extends AbstractPolyProcessor {
 		}
 		// tweak return type
 		if (funExpr instanceof ArrowFunction) {
+			log(0, "===START of special handling of single-expression arrow function");
 			// NOTE: the next line requires the type of 'funExpr' and types of fpars to be in cache! For example:
 			//   function <T> foo(p: {function(int):T}) {return undefined;}
 			//   foo( (i) => [i] );
 			tweakReturnTypeOfSingleExpressionArrowFunction(G, cache, funExpr, resultSolved);
+			log(0, "===END of special handling of single-expression arrow function");
 		}
 	}
 
@@ -300,11 +302,13 @@ package class PolyProcessor_FunctionExpression extends AbstractPolyProcessor {
 		if (!arrFun.isSingleExprImplicitReturn) {
 			return; // not applicable
 		}
-		log(0, "===START of special handling of single-expression arrow function");
 		// Step 1) process arrFun's body, which was postponed earlier according to ASTProcessor#isPostponedNode(EObject)
 		// Rationale: the body of a single-expression arrow function isn't a true block, so we do not have to
 		//            postpone it AND we need its types in the next step.
 		val block = arrFun.body;
+		if (block === null) {
+			return; // broken AST
+		}
 		if(!cache.postponedSubTrees.remove(block)) {
 			throw new IllegalStateException("body of single-expression arrow function not among postponed subtrees, in resource: " + arrFun.eResource.URI);
 		}
@@ -312,6 +316,9 @@ package class PolyProcessor_FunctionExpression extends AbstractPolyProcessor {
 		// Step 2) adjust arrFun's return type stored in arrFunTypeRef (if required)
 		var didTweakReturnType = false;
 		val expr = arrFun.getSingleExpression();
+		if (expr === null) {
+			return; // broken AST
+		}
 		val exprTypeRef = cache.getType(expr).value; // must now be in cache, because we just processed arrFun's body
 		if (TypeUtils.isVoid(exprTypeRef)) {
 			// the actual type of 'expr' is void
@@ -344,7 +351,6 @@ package class PolyProcessor_FunctionExpression extends AbstractPolyProcessor {
 		if(!didTweakReturnType) {
 			log(1, "tweaking of return type not required");
 		}
-		log(0, "===END of special handling of single-expression arrow function");
 	}
 
 	/**
diff --git a/tests/org.eclipse.n4js.smoke.tests/src/org/eclipse/n4js/smoke/tests/GeneratedSmokeTestCases4.xtend b/tests/org.eclipse.n4js.smoke.tests/src/org/eclipse/n4js/smoke/tests/GeneratedSmokeTestCases4.xtend
index 66391ad7a7..b19ddbd626 100644
--- a/tests/org.eclipse.n4js.smoke.tests/src/org/eclipse/n4js/smoke/tests/GeneratedSmokeTestCases4.xtend
+++ b/tests/org.eclipse.n4js.smoke.tests/src/org/eclipse/n4js/smoke/tests/GeneratedSmokeTestCases4.xtend
@@ -3121,4 +3121,15 @@ class GeneratedSmokeTestCases4 {
 			}
 		'''.assertNoException
 	}
+
+	/**
+	 * GH-616
+	 */
+	@Test
+	def void test_GH_616() {
+		// removing the second dot removes the exception
+		'''
+			let r = (v) => v..foo();
+		'''.assertNoException
+	}
 }