diff --git a/opengl/tools/glgen/src/JniCodeEmitter.java b/opengl/tools/glgen/src/JniCodeEmitter.java
index d5e2d34..b1bd1fd 100644
--- a/opengl/tools/glgen/src/JniCodeEmitter.java
+++ b/opengl/tools/glgen/src/JniCodeEmitter.java
@@ -1073,6 +1073,7 @@
                 String decl = type.getDeclaration();
                 needsExit = true;
                 out.println(indent + "if (!" + cname + ") {");
+                out.println(indent + indent + "_exception = 1;");
                 out.println(indent + indent +
                             "_exceptionType = \"java/lang/IllegalArgumentException\";");
                 out.println(indent + indent +