diff --git a/build/shared/lib/languages/PDE.properties b/build/shared/lib/languages/PDE.properties
index 6203e7527..3c88bfd91 100644
--- a/build/shared/lib/languages/PDE.properties
+++ b/build/shared/lib/languages/PDE.properties
@@ -415,6 +415,7 @@ editor.status.bad.generic = Possibly missing type in generic near '%s'?
 editor.status.bad.identifier = Bad identifier? Did you forget a variable or start an identifier with digits near '%s'?
 editor.status.bad.parameter = Error on parameter or method declaration near '%s'?
 editor.status.bad.import = Import not allowed here.
+editor.status.bad.mixed_mode = You may be mixing active and static modes which is not allowed.
 editor.status.extraneous = Incomplete statement or extra code near '%s'?
 editor.status.mismatched = Missing operator, semicolon, or '}' near '%s'?
 editor.status.missing.name = Missing name or ; near '%s'?
@@ -644,4 +645,4 @@ movie_maker.progress.creating_output_file = Creating output file
 movie_maker.progress.initializing = Initializing...
 movie_maker.progress.processing = Processing %s.
 
-movie_maker.progress.handling_frame = Converting frame %s of %s...
\ No newline at end of file
+movie_maker.progress.handling_frame = Converting frame %s of %s...
diff --git a/build/shared/lib/languages/PDE_es.properties b/build/shared/lib/languages/PDE_es.properties
index 2fa095889..e732a5159 100644
--- a/build/shared/lib/languages/PDE_es.properties
+++ b/build/shared/lib/languages/PDE_es.properties
@@ -387,6 +387,7 @@ editor.status.bad.identifier = Error en este identificador? Es posible que tu ol
 editor.status.bad.generic = Error en genérico cerca '%s'. Falta un tipo?
 editor.status.bad.parameter = Error en un parámetro o una declaración de método cerca '%s'?
 editor.status.bad.import = Una declaración de importación no es permitida en una definición de una clasa.
+editor.status.bad.mixed_mode = Es possible que estás usando el modo estático y activo.
 editor.status.extraneous = Una declaración incompleta o un imprevisto clave cerca '%s'?
 editor.status.mismatched = Falta un punto y coma, un operador, o un '}' cerca '%s'?
 editor.status.missing.name = Falta ; o nombre cerca '%s'?
diff --git a/java/src/processing/mode/java/preproc/PdeParseTreeListener.java b/java/src/processing/mode/java/preproc/PdeParseTreeListener.java
index b422d08f4..ac15eaef1 100644
--- a/java/src/processing/mode/java/preproc/PdeParseTreeListener.java
+++ b/java/src/processing/mode/java/preproc/PdeParseTreeListener.java
@@ -316,6 +316,23 @@ public class PdeParseTreeListener extends ProcessingBaseListener {
     footerResult = prepareFooter(rewriter, length);
   }
 
+  @Override
+  public void enterWarnMixedModes(ProcessingParser.WarnMixedModesContext ctx) {
+    pdeParseTreeErrorListenerMaybe.ifPresent((listener) -> {
+      Token token = ctx.getStart();
+      int line = token.getLine();
+      int charOffset = token.getCharPositionInLine();
+
+      listener.onError(new PdePreprocessIssue(
+        line,
+        charOffset,
+        PreprocessIssueMessageSimplifier.getLocalStr(
+            "editor.status.bad.mixed_mode"
+        )
+      ));
+    });
+  }
+
   /**
    * Endpoint for ANTLR to call when finished parsing a method invocatino.
    *
@@ -770,7 +787,7 @@ public class PdeParseTreeListener extends ProcessingBaseListener {
    * @return True if setup and false otherwise.
    */
   protected boolean isMethodSetup(ParserRuleContext declaration) {
-    if (declaration.getChildCount() < 2) {
+    if (declaration == null || declaration.getChildCount() < 2) {
       return false;
     }
     return declaration.getChild(1).getText().equals("setup");
diff --git a/java/src/processing/mode/java/preproc/Processing.g4 b/java/src/processing/mode/java/preproc/Processing.g4
index 2f9b1c6ff..2c370eff0 100644
--- a/java/src/processing/mode/java/preproc/Processing.g4
+++ b/java/src/processing/mode/java/preproc/Processing.g4
@@ -23,6 +23,7 @@ processingSketch
     :   javaProcessingSketch
     |   staticProcessingSketch
     |   activeProcessingSketch
+		|   warnMixedModes
     ;
 
 // java mode, is a compilation unit
@@ -30,20 +31,26 @@ javaProcessingSketch
     :   packageDeclaration? importDeclaration* typeDeclaration+ EOF
     ;
 
+// No method declarations, just statements
 staticProcessingSketch
     :   (importDeclaration | blockStatement)* EOF
     ;
 
 // active mode, has function definitions
 activeProcessingSketch
-	:	(importDeclaration | classBodyDeclaration)* EOF
-	;
+	  :	  (importDeclaration | classBodyDeclaration)* EOF
+	  ;
 
 variableDeclaratorId
     :   warnTypeAsVariableName
     |   IDENTIFIER ('[' ']')*
     ;
 
+warnMixedModes
+    :   (importDeclaration | classBodyDeclaration | blockStatement)* blockStatement classBodyDeclaration (importDeclaration | classBodyDeclaration | blockStatement)*
+		|   (importDeclaration | classBodyDeclaration | blockStatement)* classBodyDeclaration blockStatement (importDeclaration | classBodyDeclaration | blockStatement)*
+		;
+
 // bug #93
 // https://github.com/processing/processing/issues/93
 // prevent from types being used as variable names
diff --git a/java/test/processing/mode/java/ParserTests.java b/java/test/processing/mode/java/ParserTests.java
index 7478bf9db..e0df2f636 100644
--- a/java/test/processing/mode/java/ParserTests.java
+++ b/java/test/processing/mode/java/ParserTests.java
@@ -405,4 +405,9 @@ public class ParserTests {
     expectGood("sizethis");
   }
 
+  @Test
+  public void testMixing() {
+    expectRunnerException("mixing", 1);
+  }
+
 }