diff --git a/scripts_src/arroyo/acfist.ssl b/scripts_src/arroyo/acfist.ssl
index e630fc961..a386c05b8 100644
--- a/scripts_src/arroyo/acfist.ssl
+++ b/scripts_src/arroyo/acfist.ssl
@@ -341,7 +341,7 @@ procedure Node011 begin
 
    skill:=40-has_skill(dude_obj,SKILL_UNARMED_COMBAT);
    // Inc Unarmed to 40
-   critter_mod_skill(dude_obj,SKILL_UNARMED_COMBAT,skill);
+   call dude_mod_skill(SKILL_UNARMED_COMBAT,skill);
    Reply(127);
 
    NOption(128,Node013,004);
@@ -352,7 +352,7 @@ procedure Node012 begin
 
    skill:=55-has_skill(dude_obj,SKILL_UNARMED_COMBAT);
    // Inc Unarmed to 55
-   critter_mod_skill(dude_obj,SKILL_UNARMED_COMBAT,skill);
+   call dude_mod_skill(SKILL_UNARMED_COMBAT,skill);
    Reply(129);
 
    NOption(130,Node013,004);
diff --git a/scripts_src/arroyo/acjordan.ssl b/scripts_src/arroyo/acjordan.ssl
index 656783feb..38ee91110 100644
--- a/scripts_src/arroyo/acjordan.ssl
+++ b/scripts_src/arroyo/acjordan.ssl
@@ -228,7 +228,7 @@ procedure Node003 begin
    gfade_in(600);
 
    game_time_advance(8*ONE_GAME_HOUR);
-   critter_mod_skill(dude_obj,SKILL_MELEE,10);
+   call dude_mod_skill(SKILL_MELEE,10);
    set_local_var(LVAR_Taught_Player,1);
 
    Reply(107);
diff --git a/scripts_src/arroyo/actemvil.ssl b/scripts_src/arroyo/actemvil.ssl
index 56a2113a9..b6d5c7b29 100644
--- a/scripts_src/arroyo/actemvil.ssl
+++ b/scripts_src/arroyo/actemvil.ssl
@@ -553,8 +553,8 @@ procedure Node016a begin
 
    game_time_advance(ONE_GAME_HOUR);
 
-   critter_mod_skill(dude_obj,SKILL_UNARMED_COMBAT,10);
-   critter_mod_skill(dude_obj,SKILL_MELEE,10);
+   call dude_mod_skill(SKILL_UNARMED_COMBAT,10);
+   call dude_mod_skill(SKILL_MELEE,10);
 
    set_local_var(LVAR_Trained,1);
    call Node017;
diff --git a/scripts_src/brokhill/hcsulvan.ssl b/scripts_src/brokhill/hcsulvan.ssl
index 57154f7f5..bf1d4fe87 100644
--- a/scripts_src/brokhill/hcsulvan.ssl
+++ b/scripts_src/brokhill/hcsulvan.ssl
@@ -367,8 +367,8 @@ end
 procedure Node013a begin
    // Upgrade fight stats
    gfade_out(600);
-   critter_mod_skill(dude_obj,SKILL_UNARMED_COMBAT,10);
-   critter_mod_skill(dude_obj,SKILL_MELEE,10);
+   call dude_mod_skill(SKILL_UNARMED_COMBAT,10);
+   call dude_mod_skill(SKILL_MELEE,10);
    display_msg( mstr(164) );
    give_xp( EXP_SULLIVAN_TAUGHT_MOVES );
    game_time_advance( 6 * ONE_GAME_HOUR );
diff --git a/scripts_src/headers/upu.h b/scripts_src/headers/upu.h
index 55fc1bad2..23de4b64c 100644
--- a/scripts_src/headers/upu.h
+++ b/scripts_src/headers/upu.h
@@ -76,6 +76,18 @@ procedure closest_party_member(variable obj) begin
    return closest_who;
 end
 
+/**
+ * Modifies a player's `skill` by a given `amount`.
+ * If the skill is tagged, the magnitude of the adjustment will be at least the specified amount.
+ */
+procedure dude_mod_skill(variable skill, variable amount) begin
+   if (is_skill_tagged(skill) and (amount % 2)) then begin
+      // for rounding half away from zero
+      if (amount > 0) then amount++;
+      else amount--;
+   end
+   critter_mod_skill(dude_obj, skill, amount);
+end
 
 
 /* Reputation */
diff --git a/scripts_src/klamath/kcslim.ssl b/scripts_src/klamath/kcslim.ssl
index bf4f38fbe..6bf6f27a4 100644
--- a/scripts_src/klamath/kcslim.ssl
+++ b/scripts_src/klamath/kcslim.ssl
@@ -374,7 +374,7 @@ procedure Node990 begin
       dude_caps_adjust(-50);  // Seraph's Fix: changed from '50' to '-50'
    learn:= 2*(dude_iq);
    if (learn < 7) then learn:=7;
-   critter_mod_skill(dude_obj,SKILL_OUTDOORSMAN,learn);
+   call dude_mod_skill(SKILL_OUTDOORSMAN,learn);
    gfade_out(ONE_GAME_MINUTE);
    game_time_advance(8*ONE_GAME_HOUR);//8 hours
    gfade_in(ONE_GAME_MINUTE);
diff --git a/scripts_src/klamath/kcsmiley.ssl b/scripts_src/klamath/kcsmiley.ssl
index 74a96c75e..e6c5c9c78 100644
--- a/scripts_src/klamath/kcsmiley.ssl
+++ b/scripts_src/klamath/kcsmiley.ssl
@@ -402,7 +402,7 @@ end
 
 procedure Node940 begin
    learn:= random(1,6);
-   critter_mod_skill(dude_obj,SKILL_OUTDOORSMAN,learn);
+   call dude_mod_skill(SKILL_OUTDOORSMAN,learn);
    gfade_out(600);
    game_time_advance(game_ticks(6*3600));//6 hours
    gfade_in(600);
diff --git a/scripts_src/main/obj_dude.ssl b/scripts_src/main/obj_dude.ssl
index c1e19c567..3be3d4e3c 100644
--- a/scripts_src/main/obj_dude.ssl
+++ b/scripts_src/main/obj_dude.ssl
@@ -180,7 +180,7 @@ procedure use_obj_on_p_proc begin
          if (obj_pid(obj_being_used_with) == PID_CATS_PAW_ISSUE_5) then begin
             script_overrides;
             gfade_out(ONE_GAME_SECOND);
-               critter_mod_skill(dude_obj, SKILL_ENERGY_WEAPONS, 10);
+               call dude_mod_skill( SKILL_ENERGY_WEAPONS, 10);
                display_msg(message_str(SCRIPT_NICATPW5, 100));
             gfade_in(ONE_GAME_SECOND);
             script_overrides;
diff --git a/scripts_src/newreno/nckitty.ssl b/scripts_src/newreno/nckitty.ssl
index 040551e73..255ae346a 100644
--- a/scripts_src/newreno/nckitty.ssl
+++ b/scripts_src/newreno/nckitty.ssl
@@ -91,7 +91,7 @@ procedure Node031;
 
 #define speech_bonus_given             lvar_bit(LVAR_Flags, speech_bonus_given_bit)
 #define set_speech_bonus_given         if (speech_bonus_given == false) then begin              \
-                                          critter_mod_skill(dude_obj, SKILL_SPEECH, 3);     \
+                                          call dude_mod_skill(SKILL_SPEECH, 3);                 \
                                        end                                                      \
                                        set_lvar_bit_on(LVAR_Flags, speech_bonus_given_bit)
 
diff --git a/scripts_src/newreno/ncliljes.ssl b/scripts_src/newreno/ncliljes.ssl
index 1b4fe2f02..301654f7c 100644
--- a/scripts_src/newreno/ncliljes.ssl
+++ b/scripts_src/newreno/ncliljes.ssl
@@ -376,7 +376,7 @@ variable knife_skill_bonus := 5;
       end else begin
          display_mstr(2000);
       end
-      critter_mod_skill(dude_obj, SKILL_MELEE, knife_skill_bonus);
+      call dude_mod_skill(SKILL_MELEE, knife_skill_bonus);
    gfade_in(5);
 end
 
diff --git a/scripts_src/newreno/ncmason.ssl b/scripts_src/newreno/ncmason.ssl
index 8df760d3d..d1e314c52 100644
--- a/scripts_src/newreno/ncmason.ssl
+++ b/scripts_src/newreno/ncmason.ssl
@@ -841,7 +841,7 @@ procedure Node052 begin
    Reply(725);
    set_taught;
    game_time_advance(ONE_GAME_HOUR);
-   critter_mod_skill(dude_obj, SKILL_ENERGY_WEAPONS, 5);
+   call dude_mod_skill(SKILL_ENERGY_WEAPONS, 5);
    gfade_in(5);
    BOption(726, Node051, 006);
    BOption(643, Node046, 004);
diff --git a/scripts_src/newreno/nicatpw5.ssl b/scripts_src/newreno/nicatpw5.ssl
index d2c44e23d..40daeec2c 100644
--- a/scripts_src/newreno/nicatpw5.ssl
+++ b/scripts_src/newreno/nicatpw5.ssl
@@ -35,7 +35,7 @@ end
 procedure use_p_proc begin
    script_overrides;
    gfade_out(ONE_GAME_SECOND);
-      critter_mod_skill(dude_obj, SKILL_ENERGY_WEAPONS, 10);
+      call dude_mod_skill(SKILL_ENERGY_WEAPONS, 10);
       display_mstr(100);
    gfade_in(ONE_GAME_SECOND);
    scr_return(1);
diff --git a/scripts_src/newreno/nidermal.ssl b/scripts_src/newreno/nidermal.ssl
index 7f72a8d08..d0065bd32 100644
--- a/scripts_src/newreno/nidermal.ssl
+++ b/scripts_src/newreno/nidermal.ssl
@@ -32,7 +32,7 @@ end
 procedure use_p_proc begin
    display_mstr(100);
    give_xp(EXP_NEW_RENO_USE_DERMAL);
-   critter_mod_skill(dude_obj, SKILL_SPEECH, 10);
+   call dude_mod_skill(SKILL_SPEECH, 10);
    dude_floater(200);
    scr_return(1);
 end
diff --git a/scripts_src/newreno/nif2hint.ssl b/scripts_src/newreno/nif2hint.ssl
index b1076fb7b..10ba19150 100644
--- a/scripts_src/newreno/nif2hint.ssl
+++ b/scripts_src/newreno/nif2hint.ssl
@@ -34,7 +34,7 @@ procedure Node001;
 
 #define read_book_bit                  bit_10
 
-#define max_skill(x)                   critter_mod_skill(dude_obj, x, (300 - (has_skill(dude_obj, x))))
+#define max_skill(x)                   call dude_mod_skill(x, (300 - (has_skill(dude_obj, x))))
 
 #define read_book                      lvar_bit(LVAR_Flags, read_book_bit )
 
diff --git a/scripts_src/newreno/nimedica.ssl b/scripts_src/newreno/nimedica.ssl
index 445ee91c7..fbe2861e7 100644
--- a/scripts_src/newreno/nimedica.ssl
+++ b/scripts_src/newreno/nimedica.ssl
@@ -32,7 +32,7 @@ end
 procedure use_p_proc begin
    display_mstr(100);
    give_xp(EXP_NEW_RENO_USE_MEDICAL);
-   critter_mod_skill(dude_obj, SKILL_DOCTOR, 10);
+   call dude_mod_skill(SKILL_DOCTOR, 10);
    dude_floater(200);
    scr_return(1);
 end
\ No newline at end of file
diff --git a/scripts_src/sanfran/fcdragon.ssl b/scripts_src/sanfran/fcdragon.ssl
index 7836d577a..922972fa3 100644
--- a/scripts_src/sanfran/fcdragon.ssl
+++ b/scripts_src/sanfran/fcdragon.ssl
@@ -1172,7 +1172,7 @@ procedure learn2 begin
    fadein(1);
    float_msg(self_obj, mstr(218), FLOAT_MSG_NORMAL);
    display_msg(mstr(219));
-   critter_mod_skill(dude_obj, SKILL_UNARMED_COMBAT, 5);
+   call dude_mod_skill(SKILL_UNARMED_COMBAT, 5);
 end
 
 procedure ReturnInven begin
diff --git a/scripts_src/sanfran/fclopan.ssl b/scripts_src/sanfran/fclopan.ssl
index cbe4cbbc6..73e3e4151 100644
--- a/scripts_src/sanfran/fclopan.ssl
+++ b/scripts_src/sanfran/fclopan.ssl
@@ -1142,7 +1142,7 @@ procedure learn2 begin
    fadein(1);
    float_msg(self_obj, mstr(218), FLOAT_MSG_NORMAL);
    display_msg(mstr(219));
-   critter_mod_skill(dude_obj, SKILL_UNARMED_COMBAT, 5);
+   call dude_mod_skill(SKILL_UNARMED_COMBAT, 5);
 end
 
 procedure ReturnInven begin
diff --git a/scripts_src/sierra/wipnchbg.ssl b/scripts_src/sierra/wipnchbg.ssl
index 815419ff0..396d1e4f5 100644
--- a/scripts_src/sierra/wipnchbg.ssl
+++ b/scripts_src/sierra/wipnchbg.ssl
@@ -47,7 +47,7 @@ procedure use_p_proc begin
        inc_local_var(LVAR_Herebefore);
        gfade_out(600);
        gfade_in(600);
-       critter_mod_skill(dude_obj,SKILL_UNARMED_COMBAT,5);
+       call dude_mod_skill(SKILL_UNARMED_COMBAT,5);
        game_time_advance(ONE_GAME_HOUR);
        display_msg(g_mstr(950));
    end
diff --git a/scripts_src/vault13/oscomptr.ssl b/scripts_src/vault13/oscomptr.ssl
index a7a7d3750..01e943a85 100644
--- a/scripts_src/vault13/oscomptr.ssl
+++ b/scripts_src/vault13/oscomptr.ssl
@@ -132,7 +132,7 @@ procedure look_at_p_proc begin
    else
       display_msg(mstr(101));
 
-   /*critter_mod_skill(dude_obj, SKILL_SCIENCE, 100);
+   /*call dude_mod_skill(SKILL_SCIENCE, 100);
    item:=create_object(PID_COMPUTER_VOICE_MODULE,0,0);
    add_obj_to_inven(dude_obj, item);*/