diff --git a/ext2spice/ext2hier.c b/ext2spice/ext2hier.c
index 0e352990..e2204ae8 100644
--- a/ext2spice/ext2hier.c
+++ b/ext2spice/ext2hier.c
@@ -572,11 +572,14 @@ subcktHierVisit(
  * ----------------------------------------------------------------------------
  */
 
+/* ARGSUSED */
+/* @typedef cb_extflat_hiervisitdevs_t (UNUSED) */
 int
 spcdevHierVisit(
     HierContext *hc,
     Dev *dev,		/* Dev being output */
-    float scale)	/* Scale transform for output */
+    float scale,	/* Scale transform for output */
+    ClientData cdata)	/* unused */
 {
     DevParam *plist, *pptr;
     DevTerm *gate, *source, *drain;
@@ -1150,11 +1153,14 @@ spcdevHierVisit(
  * ----------------------------------------------------------------------------
  */
 
+/* ARGSUSED */
+/* @typedef cb_extflat_hiervisitdevs_t (UNUSED) */
 int
 spcdevHierMergeVisit(
     HierContext *hc,
     Dev *dev,		/* Dev being output */
-    float scale)	/* Scale of transform (may be non-integer) */
+    float scale,	/* Scale of transform (may be non-integer) */
+    ClientData cdata)	/* unused */
 {
     DevTerm *gate, *source, *drain;
     EFNode *subnode, *snode, *dnode, *gnode;
@@ -1272,12 +1278,15 @@ spcdevHierMergeVisit(
  * ----------------------------------------------------------------------------
  */
 
+/* ARGSUSED */
+/* @typedef cb_extflat_hiervisitdevs_t (UNUSED) */
 int
 spccapHierVisit(
     HierContext *hc,
     HierName *hierName1,
     HierName *hierName2,
-    double cap)
+    double cap,
+    ClientData cdata)	/* unused */
 {
     cap = cap / 1000;
     if (fabs(cap) <= EFCapThreshold)
@@ -1574,7 +1583,7 @@ devMergeHierVisit(
     float m;
 
     if (esDistrJunct)
-	devDistJunctHierVisit(hc, dev, scale);
+	devDistJunctHierVisit(hc, dev, scale, PTR2CD(NULL));
 
     if (dev->dev_nterm < 2)
     {
@@ -1720,11 +1729,14 @@ mergeThem:
  * ----------------------------------------------------------------------------
  */
 
+/* ARGSUSED */
+/* @typedef cb_extflat_hiervisitdevs_t (UNUSED) */
 int
 devDistJunctHierVisit(
     HierContext *hc,
     Dev *dev,			/* Dev to examine */
-    float scale)		/* Scale tranform of output */
+    float scale,		/* Scale tranform of output */
+    ClientData cdata)		/* unused */
 {
     EFNode  *n;
     int i, l, w;
@@ -2195,10 +2207,10 @@ esHierVisit(
 	    devMergeList = NULL;
 	}
 	else if (esDistrJunct)
-	    EFHierVisitDevs(hcf, devDistJunctHierVisit, (ClientData)NULL);
+	    EFHierVisitDevs(hcf, devDistJunctHierVisit, PTR2CD(NULL));
 
 	/* Output devices */
-	EFHierVisitDevs(hcf, spcdevHierVisit, (ClientData)NULL);
+	EFHierVisitDevs(hcf, spcdevHierVisit, PTR2CD(NULL));
 
 	/* Output lumped parasitic resistors */
 	EFHierVisitResists(hcf, spcresistHierVisit, (ClientData)NULL);
diff --git a/ext2spice/ext2spice.h b/ext2spice/ext2spice.h
index c41c86f3..547b2b67 100644
--- a/ext2spice/ext2spice.h
+++ b/ext2spice/ext2spice.h
@@ -52,7 +52,7 @@ extern int spcdevOutNode(const HierName *prefix, const HierName *suffix, const c
 extern int spcnAP(DevTerm *dterm, EFNode *node, int resClass, float scale, char *asterm, char *psterm, float m, FILE *outf, int w);
 extern int parallelDevs(const devMerge *f1, const devMerge *f2);
 extern int nodeHspiceName(char *s);
-extern int devDistJunctHierVisit(HierContext *hc, Dev *dev, float scale);
+extern int devDistJunctHierVisit(HierContext *hc, Dev *dev, float scale, ClientData cdata); /* @typedef cb_extflat_hiervisitdevs_t (UNUSED) */
 extern int spcnAPHier(DevTerm *dterm, HierName *hierName, int resClass, float scale, char *asterm, char *psterm, float m, FILE *outf);
 extern void mergeAttr(char **a1, char **a2);
 extern int update_w(short resClass, int w, EFNode *n);
diff --git a/extflat/EFhier.c b/extflat/EFhier.c
index efc6cc38..55b26d8d 100644
--- a/extflat/EFhier.c
+++ b/extflat/EFhier.c
@@ -416,12 +416,13 @@ efHierDevKilled(hc, dev, prefix)
  * Visit all the devs in the circuit.
  * For each dev in the circuit, call the user-supplied procedure
  * (*devProc)(), which should be of the following form:
+ *   see also typedef cb_extflat_hiervisitdevs_t:
  *
- *	(*devProc)(hc, dev, scale, cdata)
- *	    HierContext *hc;
- *	    Dev *dev;
- *	    float scale;
- *	    ClientData cdata;
+ *	int (*devProc)(
+ *	    HierContext *hc,
+ *	    Dev *dev,
+ *	    float scale,
+ *	    ClientData cdata)
  *	{
  *	}
  *
@@ -442,14 +443,14 @@ efHierDevKilled(hc, dev, prefix)
  */
 
 int
-EFHierVisitDevs(hc, devProc, cdata)
-    HierContext *hc;
-    int (*devProc)();
-    ClientData cdata;
+EFHierVisitDevs(
+    HierContext *hc,
+    const cb_extflat_hiervisitdevs_t devProc,
+    ClientData cdata)
 {
     CallArg ca;
 
-    ca.ca_proc = devProc;
+    ca.ca_proc = (int (*)()) devProc;
     ca.ca_cdata = cdata;
     return efHierVisitDevs(hc, (ClientData) &ca);
 }
diff --git a/extflat/extflat.h b/extflat/extflat.h
index 9282b4ea..52270cc7 100644
--- a/extflat/extflat.h
+++ b/extflat/extflat.h
@@ -127,7 +127,8 @@ extern void EFHNOut();
 extern int  EFHierSrDefs();
 extern int  EFVisitSubcircuits();
 extern int  EFHierVisitSubcircuits();
-extern int  EFHierVisitDevs();
+typedef int (*cb_extflat_hiervisitdevs_t)(HierContext *hc, Dev *dev, float scale, ClientData cdata);
+extern int EFHierVisitDevs(HierContext *hc, const cb_extflat_hiervisitdevs_t devProc, ClientData cdata);
 extern int  EFHierVisitResists();
 extern int  EFHierVisitCaps();
 extern int  EFHierVisitNodes();