diff --git a/include/extern.h b/include/extern.h
index b5758eef7..e12f290a2 100644
--- a/include/extern.h
+++ b/include/extern.h
@@ -2249,6 +2249,7 @@ extern void mongrantswish(struct monst **);
 extern void djinni_from_bottle(struct obj *);
 extern struct monst *split_mon(struct monst *, struct monst *);
 extern const char *bottlename(void);
+extern void speed_up(long);
 
 /* ### pray.c ### */
 
diff --git a/src/potion.c b/src/potion.c
index 668068dc4..91aa6c825 100644
--- a/src/potion.c
+++ b/src/potion.c
@@ -1036,14 +1036,13 @@ peffect_speed(struct obj *otmp)
         return;
     }
 
-    if (!Very_fast) { /* wwf@doe.carleton.ca */
-        You("are suddenly moving %sfaster.", Fast ? "" : "much ");
-    } else {
-        Your("%s get new energy.", makeplural(body_part(LEG)));
-        gp.potion_unkn++;
+    speed_up(rn1(10, 100 + 60 * bcsign(otmp)));
+
+    /* non-cursed potion grants intrinsic speed */
+    if (is_speed && !otmp->cursed && !(HFast & INTRINSIC)) {
+        Your("quickness feels very natural.");
+        HFast |= FROMOUTSIDE;
     }
-    exercise(A_DEX, TRUE);
-    incr_itimeout(&HFast, rn1(10, 100 + 60 * bcsign(otmp)));
 }
 
 static void
@@ -2787,4 +2786,17 @@ split_mon(
     return mtmp2;
 }
 
+/* Character becomes very fast temporarily. */
+void
+speed_up(long duration)
+{
+   if (!Very_fast)
+       You("are suddenly moving %sfaster.", Fast ? "" : "much ");
+   else
+       Your("%s get new energy.", makeplural(body_part(LEG)));
+
+   exercise(A_DEX, TRUE);
+   incr_itimeout(&HFast, duration);
+}
+
 /*potion.c*/
diff --git a/src/zap.c b/src/zap.c
index b9327a89e..16b6b4bf6 100644
--- a/src/zap.c
+++ b/src/zap.c
@@ -2698,15 +2698,9 @@ zapyourself(struct obj *obj, boolean ordinary)
     }
 
     case WAN_SPEED_MONSTER:
-        if (!(HFast & INTRINSIC)) {
-            learn_it = TRUE;
-            if (!Fast)
-                You("speed up.");
-            else
-                Your("quickness feels more natural.");
-            exercise(A_DEX, TRUE);
-        }
-        HFast |= FROMOUTSIDE;
+        /* no longer gives intrinsic, but gives very fast speed instead */
+        speed_up(rn1(25, 50));
+        learn_it = TRUE;
         break;
 
     case WAN_SLEEP: