diff --git a/DESCRIPTION b/DESCRIPTION
index 3767c9e7..aea9d0ce 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,5 +1,5 @@
 Package: ergm
-Version: 4.8.0-7022
+Version: 4.8.0-7504
 Date: 2024-12-22
 Title: Fit, Simulate and Diagnose Exponential-Family Models for Networks
 Authors@R: c(
diff --git a/R/InitErgmTerm.operator.R b/R/InitErgmTerm.operator.R
index aab9d949..12666823 100644
--- a/R/InitErgmTerm.operator.R
+++ b/R/InitErgmTerm.operator.R
@@ -715,8 +715,6 @@ InitErgmTerm.Sum <- function(nw, arglist,...){
   nparam <- nparams[1]
 
   inputs <- unlist(wl%>%map(t))
-  inputs <- c(nf, length(inputs), inputs)
-
 
   if(is.function(a$label)){
     cns <- lapply(ms, param_names, canonical=TRUE)
@@ -770,7 +768,7 @@ InitErgmTerm.Sum <- function(nw, arglist,...){
     }
   }else offset <- FALSE
   
-  c(list(name="Sum", coef.names = coef.names, inputs=inputs, submodels=ms, emptynwstats=gs,
+  c(list(name="Sum", coef.names = coef.names, inputs=inputs, iinputs=nf, submodels=ms, emptynwstats=gs,
          dependence=dependence, offset=offset,
          ext.encode = if(ms %>% map("terms") %>% unlist(FALSE) %>% map("ext.encode") %>% compact %>% length)
                         function(el, nw0)
diff --git a/src/changestats_operator.c b/src/changestats_operator.c
index 36503f4d..bb02a7a4 100644
--- a/src/changestats_operator.c
+++ b/src/changestats_operator.c
@@ -177,18 +177,7 @@ F_CHANGESTAT_FN(f__submodel_and_summary_term){
 // Sum: Take a weighted sum of the models' statistics.
 
 I_CHANGESTAT_FN(i_Sum){
-  /*
-    inputs expected:
-    1: number of models (nms)
-    1: total length of all weight matrices (tml)
-    tml: a list of mapping matrices in row-major order
-  */
-  
-  double *inputs = INPUT_PARAM; 
-  unsigned int nms = *(inputs++);
-  unsigned int tml = *(inputs++);
-  inputs+=tml; // Jump to start of model specifications.
-  
+  unsigned int nms = *IINPUT_PARAM;
   ALLOC_STORAGE(nms, Model*, ms);
 
   SEXP submodels = getListElement(mtp->R, "submodels");
@@ -200,11 +189,9 @@ I_CHANGESTAT_FN(i_Sum){
 }
 
 C_CHANGESTAT_FN(c_Sum){
-  double *inputs = INPUT_PARAM; 
   GET_STORAGE(Model*, ms);
-  unsigned int nms = *(inputs++);
-  inputs++; //  Skip total length of weight matrices.
-  double *wts = inputs;
+  unsigned int nms = *IINPUT_PARAM;
+  double *wts = INPUT_PARAM;
 
   for(unsigned int i=0; i<nms; i++){
     Model *m = ms[i];
@@ -216,11 +203,9 @@ C_CHANGESTAT_FN(c_Sum){
 }
 
 Z_CHANGESTAT_FN(z_Sum){
-  double *inputs = INPUT_PARAM;
   GET_STORAGE(Model*, ms);
-  unsigned int nms = *(inputs++);
-  inputs++; //  Skip total length of weight matrices.
-  double *wts = inputs;
+  unsigned int nms = *IINPUT_PARAM;
+  double *wts = INPUT_PARAM;
 
   for(unsigned int i=0; i<nms; i++){
     Model *m = ms[i];
@@ -232,11 +217,9 @@ Z_CHANGESTAT_FN(z_Sum){
 }
 
 X_CHANGESTAT_FN(x_Sum){
-  double *inputs = INPUT_PARAM;
   GET_STORAGE(Model*, ms);
-  unsigned int nms = *(inputs++);
-  inputs++; //  Skip total length of weight matrices.
-  double *wts = inputs;
+  unsigned int nms = *IINPUT_PARAM;
+  double *wts = INPUT_PARAM;
 
   for(unsigned int i=0; i<nms; i++){
     Model *m = ms[i];
@@ -248,9 +231,8 @@ X_CHANGESTAT_FN(x_Sum){
 }
 
 F_CHANGESTAT_FN(f_Sum){
-  double *inputs = INPUT_PARAM; 
   GET_STORAGE(Model*, ms);
-  unsigned int nms = *(inputs++);
+  unsigned int nms = *IINPUT_PARAM;
 
   for(unsigned int i=0; i<nms; i++){
     ModelDestroy(nwp, ms[i]);
diff --git a/tests/testthat/test-Sum.R b/tests/testthat/test-term-Sum.R
similarity index 100%
rename from tests/testthat/test-Sum.R
rename to tests/testthat/test-term-Sum.R