diff --git a/doc/MAGIC.md b/doc/MAGIC.md
index c476b69c66518..25b43ee0dccf4 100644
--- a/doc/MAGIC.md
+++ b/doc/MAGIC.md
@@ -67,7 +67,7 @@ In `data/mods/Magiclysm` there is a template spell, copied here for your perusal
     "components": [requirement_id]                            // an id from a requirement, like the ones you use for crafting. spell components require to cast.
     "difficulty": 12,                                         // the difficulty to learn/cast the spell
     "max_level": 10,                                          // maximum level you can achieve in the spell
-    "exp_formula": "constant",                                // choose between "constant", "linear", "exponential".  Exp Per level: Constant: a, Linear: a(level), Exponential (probably): e^(level * b) * e^(b) * e^(-c * b) - e^(level * b) * e^(-c * b).  Defaults to exponential if no value is given.
+    "exp_formula": "constant",                                // choose between "constant", "linear", "exponential".  Exp Per level: Constant: a, Linear: a(level), Exponential (probably): e^(level * b) * e^(-c * b) * ( e^(b) - 1 ).  Defaults to exponential if no value is given.
     "experience_calc_constant_a": 1000,                       // adjusts the constants used in the experience level calculation formula.
     "experience_calc_constant_b": 0.146661,
     "experience_calc_constant_c": -62.5,
diff --git a/src/magic.cpp b/src/magic.cpp
index f63431dc8d591..ff13c5a66c571 100644
--- a/src/magic.cpp
+++ b/src/magic.cpp
@@ -201,6 +201,7 @@ std::string enum_to_string<xp_formula>( xp_formula data )
     case xp_formula::exponential: return "exponential";
     case xp_formula::linear: return "linear";
     case xp_formula::constant: return "constant";
+    case xp_formula::num_formulas: break;
     }
     cata_fatal( "Invalid xp_formula" );
 }
@@ -1668,9 +1669,6 @@ bool spell::ignore_by_species_id( const tripoint_bub_ms &p ) const
     return valid;
 }
 
-
-
-
 std::string spell::description() const
 {
     return type->description.translated();
diff --git a/src/magic.h b/src/magic.h
index 5e14d44407683..25e7fc7775ce3 100644
--- a/src/magic.h
+++ b/src/magic.h
@@ -129,12 +129,13 @@ enum class spell_shape : int {
 };
 
 enum class xp_formula : int {
-    // e^(level * b) * e^(b) * e^(-c * b) - e^(level * b) * e^(-c * b).  Probably
+    // e^(level * b) * e^(-c * b) * ( e^(b) - 1 ) per level.  Probably
     exponential,
-    // a(level)
+    // a(level) per level
     linear,
-    // a
-    constant
+    // a per level
+    constant,
+    num_formulas
 };
 
 template<>
@@ -159,7 +160,7 @@ struct enum_traits<spell_flag> {
 
 template<>
 struct enum_traits<xp_formula> {
-    static constexpr xp_formula last = xp_formula::exponential;
+    static constexpr xp_formula last = xp_formula::num_formulas;
 };
 
 struct fake_spell {