diff --git a/include/mujoco/mjplugin.h b/include/mujoco/mjplugin.h
index a9e5127c..610297bc 100644
--- a/include/mujoco/mjplugin.h
+++ b/include/mujoco/mjplugin.h
@@ -69,7 +69,7 @@ typedef struct mjpResourceProvider mjpResourceProvider;
 
 // function pointer types
 // return an mjSpec representing the decoded resource.
-typedef mjSpec* (*mjfDecode)(const mjResource* resource);
+typedef mjSpec* (*mjfDecode)(mjResource* resource);
 // return true if the given resource can be decoded.
 typedef int (*mjfCanDecode)(const mjResource* resource);
 
diff --git a/test/plugin/decoder/decoder_test.cc b/test/plugin/decoder/decoder_test.cc
index 581b0db2..58113b14 100644
--- a/test/plugin/decoder/decoder_test.cc
+++ b/test/plugin/decoder/decoder_test.cc
@@ -39,7 +39,7 @@ static mjSpec* MakeSimpleSpec() {
 }
 
 // Always returns a simple mjSpec, ignoring the resource.
-mjSpec* FakeDecode(const mjResource* resource) { return MakeSimpleSpec(); }
+mjSpec* FakeDecode(mjResource* resource) { return MakeSimpleSpec(); }
 
 // Can decode any resource that has a .fakeformat extension.
 int FakeCanDecode(const mjResource* resource) {