diff --git a/inst/include/ergm_MHproposal.h b/inst/include/ergm_MHproposal.h
index 20bdba63..db3bd54d 100644
--- a/inst/include/ergm_MHproposal.h
+++ b/inst/include/ergm_MHproposal.h
@@ -65,8 +65,10 @@ typedef struct MHProposalstruct {
   Vertex *togglehead;
   double logratio;
   int status;
-  double *inputs; /* may be used if needed, ignored if not. */
-  int *iinputs; /* may be used if needed, ignored if not. */
+  int ninputs;
+  double *inputs;
+  int niinputs;
+  int *iinputs;
   void *storage;
   void **aux_storage;
   unsigned int n_aux;
@@ -79,8 +81,11 @@ MHProposal *MHProposalInitialize(SEXP pR, Network *nwp, void **aux_storage);
 void MHProposalDestroy(MHProposal *MHp, Network *nwp);
 
 /* Helper macros */
+#define MH_N_DINPUTS MHp->ninputs
 #define MH_DINPUTS MHp->inputs
+#define MH_N_INPUTS MH_N_DINPUTS
 #define MH_INPUTS MH_DINPUTS
+#define MH_N_IINPUTS MHp->niinputs
 #define MH_IINPUTS MHp->iinputs
 
 #define Mtail (MHp->toggletail)
diff --git a/inst/include/ergm_wtMHproposal.h b/inst/include/ergm_wtMHproposal.h
index 604e8380..d5f4e750 100644
--- a/inst/include/ergm_wtMHproposal.h
+++ b/inst/include/ergm_wtMHproposal.h
@@ -66,8 +66,10 @@ typedef struct WtMHProposalstruct {
   double *toggleweight;
   double logratio;
   int status;
-  double *inputs; /* may be used if needed, ignored if not. */
-  int *iinputs; /* may be used if needed, ignored if not. */
+  int ninputs;
+  double *inputs;
+  int niinputs;
+  int *iinputs;
   void *storage;
   void **aux_storage;
   unsigned int n_aux;
@@ -79,8 +81,11 @@ WtMHProposal *WtMHProposalInitialize(SEXP pR, WtNetwork *nwp, void **aux_storage
 void WtMHProposalDestroy(WtMHProposal *MH, WtNetwork *nwp);
 
 /* Helper macros */
+#define MH_N_DINPUTS MHp->ninputs
 #define MH_DINPUTS MHp->inputs
+#define MH_N_INPUTS MH_N_DINPUTS
 #define MH_INPUTS MH_DINPUTS
+#define MH_N_IINPUTS MHp->niinputs
 #define MH_IINPUTS MHp->iinputs
 
 #define Mtail (MHp->toggletail)
diff --git a/src/MHproposal.c b/src/MHproposal.c
index a81506d6..e576638d 100644
--- a/src/MHproposal.c
+++ b/src/MHproposal.c
@@ -62,9 +62,11 @@ MHProposal *MHProposalInitialize(SEXP pR, Network *nwp, void **aux_storage){
   MHp->x_func=(void (*)(unsigned int, void *, MHProposal*, Network*)) R_FindSymbol(fn,sn,NULL);
 
   SEXP tmp = getListElement(pR, "inputs");
-  MHp->inputs=length(tmp) ? REAL(tmp) : NULL;
+  MHp->ninputs = length(tmp);
+  MHp->inputs = MHp->ninputs ? REAL(tmp) : NULL;
   tmp = getListElement(pR, "iinputs");
-  MHp->iinputs=length(tmp) ? INTEGER(tmp) : NULL;
+  MHp->niinputs = length(tmp);
+  MHp->iinputs = MHp->niinputs ? INTEGER(tmp) : NULL;
   
   /*Clean up by freeing sn and fn*/
   R_Free(fn);
diff --git a/src/wtMHproposal.c b/src/wtMHproposal.c
index b2d95f8d..9dcbe5aa 100644
--- a/src/wtMHproposal.c
+++ b/src/wtMHproposal.c
@@ -61,9 +61,11 @@ WtMHProposal *WtMHProposalInitialize(SEXP pR, WtNetwork *nwp, void **aux_storage
   MHp->x_func=(void (*)(unsigned int, void *, WtMHProposal*, WtNetwork*)) R_FindSymbol(fn,sn,NULL);
 
   SEXP tmp = getListElement(pR, "inputs");
-  MHp->inputs=length(tmp) ? REAL(tmp) : NULL;
+  MHp->ninputs = length(tmp);
+  MHp->inputs = MHp->ninputs ? REAL(tmp) : NULL;
   tmp = getListElement(pR, "iinputs");
-  MHp->iinputs=length(tmp) ? INTEGER(tmp) : NULL;
+  MHp->niinputs = length(tmp);
+  MHp->iinputs = MHp->niinputs ? INTEGER(tmp) : NULL;
 
   /*Clean up by freeing sn and fn*/
   R_Free(fn);