diff --git a/src/frontend/parse-bison.y b/src/frontend/parse-bison.y
index c99466761..bc3b55af9 100644
--- a/src/frontend/parse-bison.y
+++ b/src/frontend/parse-bison.y
@@ -123,7 +123,7 @@ one_exp:
 
 exp:
     TOK_NUM                           { $$ = PP_mknnode($1); }
-  | TOK_STR                           { $$ = PP_mksnode($1); txfree((void*)$1); }
+  | TOK_STR                           { $$ = PP_mksnode($1); txfree($1); }
 
   | exp ',' exp                       { $$ = PP_mkbnode(PT_OP_COMMA,  $1, $3); }
   | exp '+' exp                       { $$ = PP_mkbnode(PT_OP_PLUS,   $1, $3); }
@@ -139,7 +139,7 @@ exp:
   | '~' exp                           { $$ = PP_mkunode(PT_OP_NOT, $2); }
 
   | TOK_STR '(' exp ')'               { $$ = PP_mkfnode($1, $3);
-                                        txfree((void*)$1);
+                                        txfree($1);
                                         if(!$$)
                                             YYABORT;
                                       }
diff --git a/src/include/ngspice/cmproto.h b/src/include/ngspice/cmproto.h
index 5692b5a21..89a8b3e0b 100644
--- a/src/include/ngspice/cmproto.h
+++ b/src/include/ngspice/cmproto.h
@@ -109,8 +109,8 @@ FILE *cm_stream_err(void);
 
 void *malloc_pj(size_t s);
 void *calloc_pj(size_t s1, size_t s2);
-void *realloc_pj(void *ptr, size_t s);
-void  free_pj(void *ptr);
+void *realloc_pj(const void *ptr, size_t s);
+void  free_pj(const void *ptr);
 
 FILE *fopen_with_path(const char *path, const char *mode);
 
diff --git a/src/include/ngspice/dllitf.h b/src/include/ngspice/dllitf.h
index 4df1822ad..e865c1d8e 100644
--- a/src/include/ngspice/dllitf.h
+++ b/src/include/ngspice/dllitf.h
@@ -70,11 +70,11 @@ struct coreInfo_t {
   /*Other stuff*/
 	void *    ((*dllitf_malloc_pj)(size_t));
 	void *    ((*dllitf_calloc_pj)(size_t, size_t));
-	void *    ((*dllitf_realloc_pj)(void *, size_t));
-	void      ((*dllitf_free_pj)(void *));
+	void *    ((*dllitf_realloc_pj)(const void *, size_t));
+	void      ((*dllitf_free_pj)(const void *));
 	void *    ((*dllitf_tmalloc)(size_t));
-	void *    ((*dllitf_trealloc)(void *, size_t));
-	void      ((*dllitf_txfree)(void *));
+	void *    ((*dllitf_trealloc)(const void *, size_t));
+	void      ((*dllitf_txfree)(const void *));
 };
 
 #endif
diff --git a/src/include/ngspice/memory.h b/src/include/ngspice/memory.h
index fee10b991..ef259e185 100644
--- a/src/include/ngspice/memory.h
+++ b/src/include/ngspice/memory.h
@@ -10,8 +10,8 @@
 #ifndef HAVE_LIBGC
 
 extern void *tmalloc(size_t num);
-extern void *trealloc(void *str, size_t num);
-extern void txfree(void *ptr);
+extern void *trealloc(const void *str, size_t num);
+extern void txfree(const void *ptr);
 
 #define tfree(x) (txfree(x), (x) = 0)
 
diff --git a/src/maths/sparse/spdefs.h b/src/maths/sparse/spdefs.h
index 7efe6a2a8..9ff853183 100644
--- a/src/maths/sparse/spdefs.h
+++ b/src/maths/sparse/spdefs.h
@@ -366,8 +366,8 @@ typedef  struct
 /* Allocation */
 
 extern void * tmalloc(size_t);
-extern void   txfree(void *);
-extern void * trealloc(void *, size_t);
+extern void   txfree(const void *);
+extern void * trealloc(const void *, size_t);
 
 #define SP_MALLOC(type,number)  (type *) tmalloc((size_t)(number) * sizeof(type))
 #define SP_REALLOC(ptr,type,number) \
diff --git a/src/misc/alloc.c b/src/misc/alloc.c
index 7f4d5e548..76d171cca 100644
--- a/src/misc/alloc.c
+++ b/src/misc/alloc.c
@@ -85,7 +85,7 @@ tmalloc(size_t num)
 
 
 void *
-trealloc(void *ptr, size_t num)
+trealloc(const void *ptr, size_t num)
 {
   void *s;
 /*saj*/
@@ -95,7 +95,7 @@ trealloc(void *ptr, size_t num)
 #endif
   if (!num) {
     if (ptr)
-      free(ptr);
+      free((void*) ptr);
     return NULL;
   }
 
@@ -108,7 +108,7 @@ trealloc(void *ptr, size_t num)
 #elif defined SHARED_MODULE
   mutex_lock(&allocMutex);
 #endif
-    s = realloc(ptr, num);
+    s = realloc((void*) ptr, num);
 /*saj*/
 #ifdef TCL_MODULE
   Tcl_MutexUnlock(alloc);
@@ -129,7 +129,7 @@ trealloc(void *ptr, size_t num)
 
 
 void
-txfree(void *ptr)
+txfree(const void *ptr)
 {
 /*saj*/
 #ifdef TCL_MODULE
@@ -141,7 +141,7 @@ txfree(void *ptr)
   mutex_lock(&allocMutex);
 #endif
 	if (ptr)
-		free(ptr);
+		free((void*) ptr);
 /*saj*/
 #ifdef TCL_MODULE
   Tcl_MutexUnlock(alloc);
diff --git a/src/misc/alloc.h b/src/misc/alloc.h
index 083106c4d..b310e3cba 100644
--- a/src/misc/alloc.h
+++ b/src/misc/alloc.h
@@ -8,8 +8,8 @@
 
 #ifndef HAVE_LIBGC
 void * tmalloc(size_t num);
-void * trealloc(void *ptr, size_t num);
-void txfree(void *ptr);
+void * trealloc(const void *ptr, size_t num);
+void txfree(const void *ptr);
 #endif
 
 #endif
diff --git a/src/spicelib/parser/inpptree-parser.y b/src/spicelib/parser/inpptree-parser.y
index f52dec2f2..0c6bccadf 100644
--- a/src/spicelib/parser/inpptree-parser.y
+++ b/src/spicelib/parser/inpptree-parser.y
@@ -84,7 +84,7 @@ expression: exp
 
 exp:
     TOK_NUM                           { $$ = PT_mknnode($1); }
-  | TOK_STR                           { $$ = PT_mksnode($1, ckt); txfree((void*)$1); }
+  | TOK_STR                           { $$ = PT_mksnode($1, ckt); txfree($1); }
 
   | exp '+' exp                       { $$ = PT_mkbnode("+", $1, $3); }
   | exp '-' exp                       { $$ = PT_mkbnode("-", $1, $3); }
@@ -100,7 +100,7 @@ exp:
   | TOK_STR '(' nonempty_arglist ')'  { $$ = PT_mkfnode($1, $3);
                                         if (!$$)
                                             YYERROR;
-                                        txfree((void*)$1); }
+                                        txfree($1); }
 
   | TOK_pnode
 
diff --git a/src/xspice/cm/cmexport.c b/src/xspice/cm/cmexport.c
index 5dabf80bd..cf16cbbe0 100644
--- a/src/xspice/cm/cmexport.c
+++ b/src/xspice/cm/cmexport.c
@@ -9,7 +9,7 @@ static void *tcalloc(size_t a, size_t b) {
 }
 
 #ifdef HAVE_LIBGC
-static void no_free(void *p) {
+static void no_free(const void *p) {
   NG_IGNORE(p);
 }
 #endif
diff --git a/src/xspice/cmpp/pp_lst.c b/src/xspice/cmpp/pp_lst.c
index da11fb339..257bb3581 100644
--- a/src/xspice/cmpp/pp_lst.c
+++ b/src/xspice/cmpp/pp_lst.c
@@ -53,11 +53,6 @@ NON-STANDARD FEATURES
 #include  <string.h>
 
 
-/*
-void    *malloc(unsigned size);
-void    *realloc(void *ptr, unsigned size);
-*/
-
 /* *********************************************************************** */
 
 /*
diff --git a/src/xspice/enh/enhtrans.c b/src/xspice/enh/enhtrans.c
index 954ec28a3..de5b4eee6 100644
--- a/src/xspice/enh/enhtrans.c
+++ b/src/xspice/enh/enhtrans.c
@@ -40,10 +40,6 @@ NON-STANDARD FEATURES
 
 /*=== FUNCTION PROTOTYPES ===*/
 
-//void free(void *); //ka removed compiler error
-/* int  atoi(char *);  */
-
-
 /*=== INCLUDE FILES ===*/
 
 
diff --git a/src/xspice/icm/dlmain.c b/src/xspice/icm/dlmain.c
index ab228ca0b..75b1ab341 100644
--- a/src/xspice/icm/dlmain.c
+++ b/src/xspice/icm/dlmain.c
@@ -67,8 +67,8 @@ extern CM_EXPORT void *CMudnNum(void);
 extern CM_EXPORT void *CMgetCoreItfPtr(void);
 
 extern void *tmalloc(size_t num);
-extern void *trealloc(void *str, size_t num);
-extern void txfree(void *ptr);
+extern void *trealloc(const void *str, size_t num);
+extern void txfree(const void *ptr);
 
 
 // This one returns the device table
@@ -386,11 +386,11 @@ void * calloc_pj(size_t s1, size_t s2) {
 	return (coreitf->dllitf_calloc_pj)(s1,s2);
 }
 
-void * realloc_pj(void *ptr, size_t s) {
+void * realloc_pj(const void *ptr, size_t s) {
 	return (coreitf->dllitf_realloc_pj)(ptr,s);
 }
 
-void free_pj(void *ptr) {
+void free_pj(const void *ptr) {
 	(coreitf->dllitf_free_pj)(ptr);
 }
 
@@ -398,11 +398,11 @@ void * tmalloc(size_t s) {
 	return (coreitf->dllitf_tmalloc)(s);
 }
 
-void * trealloc(void *ptr, size_t s) {
+void * trealloc(const void *ptr, size_t s) {
 	return (coreitf->dllitf_trealloc)(ptr,s);
 }
 
-void txfree(void *ptr) {
+void txfree(const void *ptr) {
 	(coreitf->dllitf_txfree)(ptr);
 }
 
diff --git a/src/xspice/xspice.c b/src/xspice/xspice.c
index bfd277710..c43d58f0a 100644
--- a/src/xspice/xspice.c
+++ b/src/xspice/xspice.c
@@ -8,7 +8,7 @@ static void *tcalloc(size_t a, size_t b) {
   return tmalloc(a*b);          /* FIXME, tcalloc must zero !?!? */
 }
 
-static void no_free(void *p) {
+static void no_free(const void *p) {
   NG_IGNORE(p);
 }