diff --git a/dbg_mlc.c b/dbg_mlc.c
index 49102c7c1..c09cf5d0a 100644
--- a/dbg_mlc.c
+++ b/dbg_mlc.c
@@ -492,23 +492,27 @@ GC_API void GC_CALL GC_debug_register_displacement(size_t offset)
 }
 
 #ifdef GC_ADD_CALLER
-# if defined(HAVE_DLADDR) && defined(GC_HAVE_RETURN_ADDR_PARENT)
+# if defined(HAVE_DLADDR) && defined(GC_HAVE_RETURN_ADDR_PARENT) \
+     && defined(FUNCPTR_IS_DATAPTR)
 #   include <dlfcn.h>
 
-    STATIC void GC_caller_func_offset(word ad, const char **symp, int *offp)
+    STATIC void GC_caller_func_offset(GC_return_addr_t ra, const char **symp,
+                                      int *offp)
     {
       Dl_info caller;
 
-      if (ad && dladdr((void *)ad, &caller) && caller.dli_sname != NULL) {
+      if (ra != 0 && dladdr((void *)ra, &caller)
+          && caller.dli_sname != NULL) {
         *symp = caller.dli_sname;
-        *offp = (int)((char *)ad - (char *)caller.dli_saddr);
+        *offp = (int)((ptr_t)ra - (ptr_t)caller.dli_saddr);
       }
       if (NULL == *symp) {
         *symp = "unknown";
+        /* Note: *offp is unchanged.    */
       }
     }
 # else
-#   define GC_caller_func_offset(ad, symp, offp) (void)(*(symp) = "unknown")
+#   define GC_caller_func_offset(ra, symp, offp) (void)(*(symp) = "unknown")
 # endif
 #endif /* GC_ADD_CALLER */
 
diff --git a/include/gc/gc.h b/include/gc/gc.h
index feb364e82..451ea56ba 100644
--- a/include/gc/gc.h
+++ b/include/gc/gc.h
@@ -1034,9 +1034,17 @@ GC_API GC_ATTR_MALLOC GC_ATTR_ALLOC_SIZE(1) void * GC_CALL
 GC_API GC_ATTR_MALLOC GC_ATTR_ALLOC_SIZE(1) void * GC_CALL
         GC_malloc_atomic_ignore_off_page(size_t /* lb */);
 
+#if (defined(GC_CAN_SAVE_CALL_STACKS) || defined(GC_ADD_CALLER)) \
+    && !defined(GC_RETURN_ADDR_T_DEFINED)
+  /* A type to hold a function return address (pointer).  Never used    */
+  /* for calling a function.                                            */
+  typedef void (*GC_return_addr_t)(void);
+# define GC_RETURN_ADDR_T_DEFINED
+#endif /* GC_CAN_SAVE_CALL_STACKS || GC_ADD_CALLER */
+
 #ifdef GC_ADD_CALLER
 # define GC_EXTRAS GC_RETURN_ADDR, __FILE__, __LINE__
-# define GC_EXTRA_PARAMS GC_word ra, const char * s, int i
+# define GC_EXTRA_PARAMS GC_return_addr_t ra, const char * s, int i
 #else
 # define GC_EXTRAS __FILE__, __LINE__
 # define GC_EXTRA_PARAMS const char * s, int i
diff --git a/include/gc/gc_config_macros.h b/include/gc/gc_config_macros.h
index 3285d0cf1..5de58dcce 100644
--- a/include/gc/gc_config_macros.h
+++ b/include/gc/gc_config_macros.h
@@ -330,7 +330,7 @@
 
 #if defined(__sgi) && !defined(__GNUC__) && _COMPILER_VERSION >= 720
 # define GC_ADD_CALLER
-# define GC_RETURN_ADDR (GC_word)__return_address
+# define GC_RETURN_ADDR (GC_return_addr_t)__return_address
 #endif
 
 #if defined(__linux__) || defined(__GLIBC__)
@@ -356,11 +356,8 @@
 # define GC_HAVE_BUILTIN_BACKTRACE
 #endif
 
-#if defined(GC_HAVE_BUILTIN_BACKTRACE) && !defined(GC_CAN_SAVE_CALL_STACKS)
-# define GC_CAN_SAVE_CALL_STACKS
-#endif
-
-#if defined(__sparc__)
+#if defined(GC_HAVE_BUILTIN_BACKTRACE) && !defined(GC_CAN_SAVE_CALL_STACKS) \
+    || defined(__sparc__)
 # define GC_CAN_SAVE_CALL_STACKS
 #endif
 
@@ -380,19 +377,20 @@
 # if GC_GNUC_PREREQ(2, 95)
     /* gcc knows how to retrieve return address, but we don't know      */
     /* how to generate call stacks.                                     */
-#   define GC_RETURN_ADDR (GC_word)__builtin_return_address(0)
+#   define GC_RETURN_ADDR (GC_return_addr_t)__builtin_return_address(0)
 #   if GC_GNUC_PREREQ(4, 0) && (defined(__i386__) || defined(__amd64__) \
                         || defined(__x86_64__) /* and probably others... */) \
        && !defined(GC_NO_RETURN_ADDR_PARENT)
 #     define GC_HAVE_RETURN_ADDR_PARENT
 #     define GC_RETURN_ADDR_PARENT \
-        (GC_word)__builtin_extract_return_addr(__builtin_return_address(1))
+                (GC_return_addr_t)__builtin_extract_return_addr( \
+                                        __builtin_return_address(1))
             /* Note: a compiler might complain that calling                 */
             /* __builtin_return_address with a nonzero argument is unsafe.  */
 #   endif
 # else
     /* Just pass 0 for gcc compatibility.       */
-#   define GC_RETURN_ADDR 0
+#   define GC_RETURN_ADDR ((GC_return_addr_t)0)
 # endif
 #endif /* !GC_CAN_SAVE_CALL_STACKS */
 
diff --git a/include/private/gc_priv.h b/include/private/gc_priv.h
index cb7dfd8bc..8431d476e 100644
--- a/include/private/gc_priv.h
+++ b/include/private/gc_priv.h
@@ -456,7 +456,7 @@ EXTERN_C_BEGIN
 
 #ifdef NEED_CALLINFO
   struct callinfo {
-    word ci_pc; /* pc of caller, not callee */
+    GC_return_addr_t ci_pc; /* pc of caller, not callee */
 #   if NARGS > 0
       GC_hidden_pointer ci_arg[NARGS]; /* hide to avoid retention */
 #   endif
diff --git a/os_dep.c b/os_dep.c
index 65701141b..8bd14603a 100644
--- a/os_dep.c
+++ b/os_dep.c
@@ -5276,7 +5276,7 @@ GC_API int GC_CALL GC_get_pages_executable(void)
                                         struct callinfo info[NFRAMES])
           {
             GC_ASSERT(I_HOLD_LOCK());
-            info[0].ci_pc = (word)(&GC_save_callers_no_unlock);
+            info[0].ci_pc = (GC_return_addr_t)(&GC_save_callers_no_unlock);
             BZERO(&info[1], sizeof(void *) * (NFRAMES - 1));
           }
 #       endif
@@ -5295,7 +5295,7 @@ GC_API int GC_CALL GC_get_pages_executable(void)
         GC_STATIC_ASSERT(sizeof(struct callinfo) == sizeof(void *));
 #       ifdef REDIRECT_MALLOC
           if (GC_in_save_callers) {
-            info[0].ci_pc = (word)(&GC_save_callers);
+            info[0].ci_pc = (GC_return_addr_t)(&GC_save_callers);
             BZERO(&info[1], sizeof(void *) * (NFRAMES - 1));
             return;
           }
@@ -5363,11 +5363,11 @@ GC_API int GC_CALL GC_get_pages_executable(void)
             int i;
 #         endif
 
-          info[nframes].ci_pc = fp -> FR_SAVPC;
+          info[nframes].ci_pc = (GC_return_addr_t)(fp -> FR_SAVPC);
 #         if NARGS > 0
             for (i = 0; i < NARGS; i++) {
               info[nframes].ci_arg[i] =
-                GC_HIDE_NZ_POINTER((void *)(signed_word)(fp -> fr_arg[i]));
+                        GC_HIDE_NZ_POINTER((void *)(fp -> fr_arg[i]));
             }
 #         endif
         }
@@ -5437,9 +5437,9 @@ GC_API int GC_CALL GC_get_pages_executable(void)
           char buf[40];
           char *name;
 #         if defined(GC_HAVE_BUILTIN_BACKTRACE) \
-             && !defined(GC_BACKTRACE_SYMBOLS_BROKEN)
-            char **sym_name =
-              backtrace_symbols((void **)(&(info[i].ci_pc)), 1);
+             && !defined(GC_BACKTRACE_SYMBOLS_BROKEN) \
+             && defined(FUNCPTR_IS_DATAPTR)
+            char **sym_name = backtrace_symbols((void **)&info[i].ci_pc, 1);
             if (sym_name != NULL) {
               name = sym_name[0];
             } else
@@ -5550,7 +5550,8 @@ GC_API int GC_CALL GC_get_pages_executable(void)
 #         endif /* LINUX */
           GC_err_printf("\t\t%s\n", name);
 #         if defined(GC_HAVE_BUILTIN_BACKTRACE) \
-             && !defined(GC_BACKTRACE_SYMBOLS_BROKEN)
+             && !defined(GC_BACKTRACE_SYMBOLS_BROKEN) \
+             && defined(FUNCPTR_IS_DATAPTR)
             if (sym_name != NULL)
               free(sym_name);   /* May call GC_[debug_]free; that's OK  */
 #         endif