4 files changed, 4 insertions, 4 deletions
diff --git a/include/ruby/assert.h b/include/ruby/assert.h
index 9b70d7103e..b0bbdd2c14 100644
--- a/include/ruby/assert.h
+++ b/include/ruby/assert.h
@@ -167,7 +167,7 @@ RBIMPL_SYMBOL_EXPORT_END()
 #define RUBY_ASSERT_ALWAYS(expr) RUBY_ASSERT_MESG((expr), #expr)
 
 /**
- * Asserts that the given expression is truthy iff #RUBY_DEBUG is truthy.
+ * Asserts that the given expression is truthy if and only if #RUBY_DEBUG is truthy.
  *
  * @param  expr  What supposedly evaluates to true.
  */
diff --git a/include/ruby/internal/attr/const.h b/include/ruby/internal/attr/const.h
index d5b8da0c2d..b1f27e2606 100644
--- a/include/ruby/internal/attr/const.h
+++ b/include/ruby/internal/attr/const.h
@@ -36,7 +36,7 @@
 # define RBIMPL_ATTR_CONST() /* void */
 #endif
 
-/** Enables #RBIMPL_ATTR_CONST iff. ! #RUBY_DEBUG. */
+/** Enables #RBIMPL_ATTR_CONST if and only if. ! #RUBY_DEBUG. */
 #if !RUBY_DEBUG
 # define RBIMPL_ATTR_CONST_UNLESS_DEBUG() RBIMPL_ATTR_CONST()
 #else
diff --git a/include/ruby/internal/attr/constexpr.h b/include/ruby/internal/attr/constexpr.h
index 96b010ce6f..dabb72434b 100644
--- a/include/ruby/internal/attr/constexpr.h
+++ b/include/ruby/internal/attr/constexpr.h
@@ -75,7 +75,7 @@
 # define RBIMPL_ATTR_CONSTEXPR(_) /* void */
 #endif
 
-/** Enables #RBIMPL_ATTR_CONSTEXPR iff. ! #RUBY_DEBUG. */
+/** Enables #RBIMPL_ATTR_CONSTEXPR if and only if. ! #RUBY_DEBUG. */
 #if !RUBY_DEBUG
 # define RBIMPL_ATTR_CONSTEXPR_UNLESS_DEBUG(_) RBIMPL_ATTR_CONSTEXPR(_)
 #else
diff --git a/include/ruby/internal/attr/pure.h b/include/ruby/internal/attr/pure.h
index 1a10540ef3..4416c25aa0 100644
--- a/include/ruby/internal/attr/pure.h
+++ b/include/ruby/internal/attr/pure.h
@@ -33,7 +33,7 @@
 # define RBIMPL_ATTR_PURE() /* void */
 #endif
 
-/** Enables #RBIMPL_ATTR_PURE iff. ! #RUBY_DEBUG. */
+/** Enables #RBIMPL_ATTR_PURE if and only if. ! #RUBY_DEBUG. */
 #if !RUBY_DEBUG
 # define RBIMPL_ATTR_PURE_UNLESS_DEBUG() RBIMPL_ATTR_PURE()
 #else