diff --git a/ModeliRpc.proto b/ModeliRpc.proto
index 6c6b3cc274ec0533541315cc8da8b9a9d933dd81..cbd25e310b53596b89c744eaf2d9f7b5715d40f6 100644
--- a/ModeliRpc.proto
+++ b/ModeliRpc.proto
@@ -38,6 +38,9 @@ service ModeliBackend {
     rpc NewValues (NewValuesRequest) returns (stream NewValuesResponse);
     // Stream log messages to the client
     rpc Log (LogRequest) returns (stream LogResponse);
+
+    // Modify the simulation step size
+    rpc SetStepSize (SetStepSizeRequest) returns (SetStepSizeResponse);
 }
 
 // The metadata of a ChannelLink
@@ -182,4 +185,10 @@ message LogResponse {
     string instance_name = 1;
     int32 status = 2;
     string message = 3;
-}
\ No newline at end of file
+}
+
+message SetStepSizeRequest {
+    double step_size = 1;
+}
+
+message SetStepSizeResponse {}
\ No newline at end of file