diff --git a/calc/calc.h b/calc/calc.h
index 27cd5eb..8a19d87 100644
--- a/calc/calc.h
+++ b/calc/calc.h
@@ -279,6 +279,7 @@ typedef struct packedvar_s {
     unsigned            pv_cond;      /* if VT_COND */
     pSym               *pv_sym;       /* if VT_DSYM */
     struct user_type   *pv_usertype;  /* if VT_USER */
+    char               *pv_prototype; /* if VT_PROCNAME: C prototype string */
     dim_t               pv_dimu;      /* if VT_ARRAY|VECTOR|MATRIX */
     struct packedvar_s *pv_next;      /* next allocated packedvar */
 } packedvar_t;
diff --git a/calc/decl.c b/calc/decl.c
index cb5f4ff..a366692 100644
--- a/calc/decl.c
+++ b/calc/decl.c
@@ -150,7 +150,7 @@ The following type declarations may be specified.  VT_REAL is the default base
 VT_INTEGER, name
 VT_REAL, name
 VT_TYPENAME, typename, name
-VT_PROCNAME, name,    
+VT_PROCNAME, name, prototype
 VT_INTEGER|VT_ARRAY, name {,dimension} ... , 0        int array, VT_BYREF implied
 VT_ARRAY, name {,dimension} ... , 0                real array, VT_BYREF implied
 These array types take array dimensions as strings rather than numbers:
@@ -220,7 +220,7 @@ packvar(unsigned vtype, ...)
 
     pvar = (packedvar_t *)malloc(sizeof(packedvar_t));
     pvar->pv_flags = vtype;
-    pvar->pv_name = pvar->pv_typename = NULL;
+    pvar->pv_name = pvar->pv_typename = pvar->pv_prototype = NULL;
     pvar->pv_cond = 0;
     pvar->pv_sym = NULL;
     pvar->pv_usertype = NULL;
@@ -246,6 +246,9 @@ packvar(unsigned vtype, ...)
 
     pvar->pv_name = va_arg(argptr, char *);
 
+    if ((vtype & VT_BASETYPE) == VT_PROCNAME)
+        pvar->pv_prototype = va_arg(argptr, char *);
+
     if (vtype & VT_ARRAY) {
         uintptr_t *dimp = pvar->pv_dimu.ut_dim;
         while (*dimp++ = va_arg(argptr, unsigned));
@@ -314,6 +317,15 @@ VARNAME(va_list     *argptr,
                                     : va_arg(*argptr, char*);
 }
 
+static char*
+VARPROTOTYPE(va_list     *argptr,
+             unsigned    decl_flags,
+             packedvar_t *pvar)
+{
+    return decl_flags & DECL_PACKED ? pvar->pv_prototype
+                                    : va_arg(*argptr, char*);
+}
+
 static char*
 VARTYPENAME(va_list     *argptr,
             unsigned    decl_flags,
@@ -546,7 +558,7 @@ DECL_NOPRINT        with this flag, we define the user type but produce no
 
 VT_INTEGER, name
 VT_REAL, name
-VT_PROCNAME, name
+VT_PROCNAME, name, prototype
 VT_INTEGER|VT_ARRAY, name {,dimension} ... , 0        int array, VT_BYREF implied
 VT_ARRAY, name {,dimension} ... , 0                real array, VT_BYREF implied
 VT_INTEGER|VT_SARRAY, name {,dimension} ... , NULL  int array, VT_BYREF implied
@@ -590,6 +602,8 @@ declare_type(FILE *F, unsigned decl_flags, ...)
                 continue;
             }
             user_type->name = va_arg(argptr, char *);
+            if ((user_type->type & VT_BASETYPE) == VT_PROCNAME)
+                (void) va_arg(argptr, char *);  /* past prototype */
             get_dims(user_type->type, &user_type->dimu, &argptr, PVNULL, 0);
             user_type->type |= VT_ISUSER;
         } 
@@ -652,7 +666,9 @@ do_declare_vars1(FILE            *F,
     static unsigned last_vtype;
     static int skip, first_name;
     static char *vname;
+    static char *last_prototype;
     static dim_t dimu;
+    char *prototype;
     uintptr_t *dimp;
     char **sdimp;
     struct user_type *user_type;
@@ -751,6 +767,14 @@ do_declare_vars1(FILE            *F,
         }
 
         vname = VARNAME(&*argptr, decl_flags, pvar);
+        prototype = NULL;
+        if ((vtype & VT_BASETYPE) == VT_PROCNAME) {
+            prototype = VARPROTOTYPE(&*argptr, decl_flags, pvar);
+            last_prototype = prototype;
+        } else if ((vtype & VT_BASETYPE) == VT_DUP &&
+                   (last_vtype & VT_BASETYPE) == VT_PROCNAME) {
+            prototype = last_prototype;
+        }
         if ((decl_flags & DECL_NUMSUFFIX) && vname) {
             esprintf(tmpvname, "%@s%@d", vname, num_suffix);
             vname = tmpvname;
@@ -814,7 +838,8 @@ do_declare_vars1(FILE            *F,
                 } else {
                     if ((Lang->flags & LANG_C_FAMILY) &&
                            (vtype & VT_BASETYPE) == VT_PROCNAME)
-                        efprintf(F, "(*%s)()", vname);
+                        efprintf(F, "(*%s)(%s)", vname,
+                                 prototype ? prototype : "");
                     else
                         efprintf(F, "%s%s", vtype & VT_BYREF ? Lang->deref : "",
                           vname);
@@ -948,6 +973,8 @@ do_declare_vars2(FILE        *F,
             first_name = 1;
         }
         vname = VARNAME(&*argptr, decl_flags, pvar);
+        if ((next_vtype & VT_BASETYPE) == VT_PROCNAME)
+            (void) VARPROTOTYPE(&*argptr, decl_flags, pvar);
         if (decl_flags & DECL_NUMSUFFIX && vname) {
             esprintf(tmpvname, "%@s%@d", vname, num_suffix);
             vname = tmpvname;
@@ -1130,6 +1157,9 @@ skip_decl(unsigned    vtype,
 
     name = va_arg(*argptr, char *);
 
+    if ((vtype & VT_BASETYPE) == VT_PROCNAME)
+        (void) va_arg(*argptr, char *);        /* past prototype */
+
     if (vtype & VT_ARRAY)
         while (va_arg(*argptr, unsigned));        /* past dimensions */
     else if (vtype & VT_SARRAY)
diff --git a/sdfast_main/main.c b/sdfast_main/main.c
index 48047bf..f7bda5c 100644
--- a/sdfast_main/main.c
+++ b/sdfast_main/main.c
@@ -561,7 +561,7 @@ if you try to steal one.\n");
 #if defined(_WIN32) && !defined(APPLIED_MOTION)
 int am_debug;
 
-EX2UI_heartbeat(void)
+void EX2UI_heartbeat(void)
 {
 }
 #endif
diff --git a/sdfast_main/sdinteg.c b/sdfast_main/sdinteg.c
index 82d7448..37a58b1 100644
--- a/sdfast_main/sdinteg.c
+++ b/sdfast_main/sdinteg.c
@@ -113,6 +113,8 @@
 void PRINT_SDINTEG(FILE *F)
 {
     char str_flt0[10], lowlmt[10];
+    char integ_func_proto[128];
+    esprintf(integ_func_proto, "%t, %t[], %t[], %t[], int*");
 
     esprintf(str_flt0, "%r", 0.);
     esprintf(lowlmt, "%@d", 0);
@@ -141,7 +143,8 @@ void PRINT_SDINTEG(FILE *F)
  */
 
     declare_proc(F, DECL_PACKED, "rk4m",
-      packvar(VT_PROCNAME,                 "func"),
+      packvar(VT_PROCNAME,                 "func",
+              integ_func_proto),
       packvar(VT_REAL,                  "time"),
       packvar(VT_SARRAY,                   "st",   "neq",              NULL),
       packvar(VT_DUP,                      "dst0"), 
@@ -238,7 +241,7 @@ void PRINT_SDINTEG(FILE *F)
 A fixed-step integrator.  Work should be dimensioned 4*neq.%}\n");
 
     declare_proc(F, 0,  "finteg",
-      VT_PROCNAME,      "func",
+      VT_PROCNAME,      "func", integ_func_proto,
       VT_REAL|VT_BYREF,        "time",
       VT_SARRAY,           "st", "neq", NULL,
       VT_DUP,                "dst",
@@ -300,7 +303,8 @@ A fixed-step integrator.  Work should be dimensioned 4*neq.%}\n");
 A variable-step integrator.  Work should be dimensioned 6*neq.%}");
 
     declare_proc(F, DECL_PACKED,  "vinteg",
-      packvar(VT_PROCNAME,              "func"),
+      packvar(VT_PROCNAME,              "func",
+              integ_func_proto),
       packvar(VT_REAL|VT_BYREF,                "time"),
       packvar(VT_SARRAY,                   "st",   "neqin",            NULL),
       packvar(VT_DUP,                        "dst"),
diff --git a/sdfast_main/sdroot.c b/sdfast_main/sdroot.c
index 24fecb7..73abfc2 100644
--- a/sdfast_main/sdroot.c
+++ b/sdfast_main/sdroot.c
@@ -160,6 +160,8 @@ void PRINT_SDROOT(FILE *F)
     char lowlmt[10],str_flt0[10];
     char uplmtntrys[15];
     char numtrys[15],maxfixits[15];
+    char root_func_proto[128];
+    esprintf(root_func_proto, "%t[], %t[], %t[]");
 
     esprintf(lowlmt, "%@d", 0);
     esprintf(str_flt0, "%r", 0.);
@@ -242,7 +244,8 @@ void PRINT_SDROOT(FILE *F)
  * the direction of movement is preserved.
  */
     declare_proc(F, DECL_PACKED, "adjvars",
-      packvar(VT_PROCNAME,                 "func"),
+      packvar(VT_PROCNAME,                 "func",
+              root_func_proto),
       packvar(VT_SARRAY,                   "vars", "nvar", NULL),
       packvar(VT_SARRAY,                   "param", Lang->unknown_len, NULL),
       packvar(VT_INTEGER,                  "nfunc"),
@@ -374,7 +377,8 @@ void PRINT_SDROOT(FILE *F)
  * by the number of evaluations of f() performed here.
  */
     declare_proc(F, DECL_PACKED, "calcjac",
-      packvar(VT_PROCNAME,                 "func"),
+      packvar(VT_PROCNAME,                 "func",
+              root_func_proto),
       packvar(VT_SARRAY,                   "vars",  "nvar",   NULL),
       packvar(VT_SARRAY,                   "param",  Lang->unknown_len, NULL),
       packvar(VT_INTEGER,                  "nfunc"),
@@ -509,7 +513,8 @@ Work arrays should be dimensioned as follows:\n\
 ====================================================================\n%}");
 
     declare_proc(F, DECL_PACKED, "root",
-      packvar(VT_PROCNAME,                 "func"),
+      packvar(VT_PROCNAME,                 "func",
+              root_func_proto),
       packvar(VT_SARRAY,                   "vars", "nvar",  NULL),
       packvar(VT_SARRAY,                   "param", Lang->unknown_len, NULL),
       packvar(VT_INTEGER,                  "nfunc"),