diff --git a/crates/oxc_semantic/src/post_transform_checker.rs b/crates/oxc_semantic/src/post_transform_checker.rs
index 9c51f23f34bd0..bdb3c638e0e9c 100644
--- a/crates/oxc_semantic/src/post_transform_checker.rs
+++ b/crates/oxc_semantic/src/post_transform_checker.rs
@@ -117,6 +117,11 @@ pub fn check_semantic_after_transform(
 ) -> Option<Vec<OxcDiagnostic>> {
     let mut errors = Errors::default();
 
+    let source_type = program.source_type;
+    if !source_type.is_typescript_definition() && !source_type.is_javascript() {
+        errors.push(format!("SourceType is not javascript: {:?}", program.source_type));
+    }
+
     // Collect `ScopeId`s, `SymbolId`s and `ReferenceId`s from AST after transformer
     let scoping_after_transform =
         Scoping { symbols: symbols_after_transform, scopes: scopes_after_transform };
diff --git a/crates/oxc_span/src/source_type/mod.rs b/crates/oxc_span/src/source_type/mod.rs
index 209fb6a0a9eb3..8b6a759e75739 100644
--- a/crates/oxc_span/src/source_type/mod.rs
+++ b/crates/oxc_span/src/source_type/mod.rs
@@ -294,6 +294,14 @@ impl SourceType {
         self
     }
 
+    #[must_use]
+    pub const fn with_javascript(mut self, yes: bool) -> Self {
+        if yes {
+            self.language = Language::JavaScript;
+        }
+        self
+    }
+
     #[must_use]
     pub const fn with_typescript(mut self, yes: bool) -> Self {
         if yes {
@@ -318,6 +326,14 @@ impl SourceType {
         self
     }
 
+    #[must_use]
+    pub const fn with_standard(mut self, yes: bool) -> Self {
+        if yes {
+            self.variant = LanguageVariant::Standard;
+        }
+        self
+    }
+
     /// Converts a file [`Path`] to [`SourceType`].
     ///
     /// ## Examples
diff --git a/crates/oxc_transformer/src/react/mod.rs b/crates/oxc_transformer/src/react/mod.rs
index 2ecfc9712b7bf..c9523b6ad43c6 100644
--- a/crates/oxc_transformer/src/react/mod.rs
+++ b/crates/oxc_transformer/src/react/mod.rs
@@ -70,6 +70,9 @@ impl<'a> React<'a> {
 
 impl<'a> Traverse<'a> for React<'a> {
     fn enter_program(&mut self, program: &mut Program<'a>, ctx: &mut TraverseCtx<'a>) {
+        if self.jsx_plugin {
+            program.source_type = program.source_type.with_standard(true);
+        }
         if self.refresh_plugin {
             self.refresh.enter_program(program, ctx);
         }
diff --git a/crates/oxc_transformer/src/typescript/mod.rs b/crates/oxc_transformer/src/typescript/mod.rs
index 243d9b2837552..609a62f118f04 100644
--- a/crates/oxc_transformer/src/typescript/mod.rs
+++ b/crates/oxc_transformer/src/typescript/mod.rs
@@ -77,6 +77,7 @@ impl<'a> Traverse<'a> for TypeScript<'a> {
             program.hashbang = None;
             program.body.clear();
         } else {
+            program.source_type = program.source_type.with_javascript(true);
             self.namespace.enter_program(program, ctx);
         }
     }