diff --git a/core/src/processing/opengl/PGL.java b/core/src/processing/opengl/PGL.java
index 964efa98a..0c2bb3e66 100644
--- a/core/src/processing/opengl/PGL.java
+++ b/core/src/processing/opengl/PGL.java
@@ -1013,7 +1013,11 @@ public class PGL {
       } catch (GLException e) {
         // Unwrap GLException so that only the causing exception is shown.
         Throwable tr = e.getCause();
-        throw new RuntimeException(tr);
+        if (tr instanceof RuntimeException) {
+          throw (RuntimeException)tr;
+        } else {
+          throw new RuntimeException(tr);
+        }
       }
     }
   }