diff --git a/src/main/java/com/google/api/generator/engine/ast/IfStatement.java b/src/main/java/com/google/api/generator/engine/ast/IfStatement.java
index 0252d61185..6451ab38ee 100644
--- a/src/main/java/com/google/api/generator/engine/ast/IfStatement.java
+++ b/src/main/java/com/google/api/generator/engine/ast/IfStatement.java
@@ -63,6 +63,10 @@ public Builder addElseIf(Expr conditionExpr, List<Statement> body) {
 
     public IfStatement build() {
       IfStatement ifStatement = autoBuild();
+      NodeValidator.checkNoNullElements(ifStatement.body(), "body", "if-statement");
+      NodeValidator.checkNoNullElements(ifStatement.elseIfs(), "else-ifs", "if-statement");
+      NodeValidator.checkNoNullElements(ifStatement.elseBody(), "else-body", "if-statement");
+
       Preconditions.checkState(
           ifStatement.conditionExpr().type().equals(TypeNode.BOOLEAN),
           "If-condition must be a boolean-typed expression");
diff --git a/src/main/java/com/google/api/generator/engine/ast/NodeValidator.java b/src/main/java/com/google/api/generator/engine/ast/NodeValidator.java
index 5eba84e936..b6eb9c6915 100644
--- a/src/main/java/com/google/api/generator/engine/ast/NodeValidator.java
+++ b/src/main/java/com/google/api/generator/engine/ast/NodeValidator.java
@@ -16,6 +16,7 @@
 
 import com.google.common.base.Preconditions;
 import java.util.Collection;
+import java.util.Map;
 import java.util.Objects;
 
 public class NodeValidator {
@@ -26,4 +27,11 @@ public static void checkNoNullElements(
         String.format(
             "Found null expression in %s %s for %s", fieldTypeName, collection, nodeContextInfo));
   }
+
+  public static void checkNoNullElements(
+      Map<?, ?> map, String fieldTypeName, String nodeContextInfo) {
+    checkNoNullElements(map.keySet(), String.format("key of %s", fieldTypeName), nodeContextInfo);
+    checkNoNullElements(
+        map.values(), String.format("values of %s", fieldTypeName), nodeContextInfo);
+  }
 }