diff --git a/Mathlib/Analysis/SpecialFunctions/JapaneseBracket.lean b/Mathlib/Analysis/SpecialFunctions/JapaneseBracket.lean
index c3a00d8725ab3..94524e35ae847 100644
--- a/Mathlib/Analysis/SpecialFunctions/JapaneseBracket.lean
+++ b/Mathlib/Analysis/SpecialFunctions/JapaneseBracket.lean
@@ -146,7 +146,8 @@ theorem integrable_one_add_norm [MeasureSpace E] [BorelSpace E] [(@volume E _).I
   -- Lower Lebesgue integral
   have : (∫⁻ a : E, ‖(1 + ‖a‖) ^ (-r)‖₊) = ∫⁻ a : E, ENNReal.ofReal ((1 + ‖a‖) ^ (-r)) :=
     lintegral_nnnorm_eq_of_nonneg fun _ => rpow_nonneg (by positivity) _
-  rw [HasFiniteIntegral, this]
+  unfold HasFiniteIntegral
+  rw [this]
   exact finite_integral_one_add_norm hnr
 #align integrable_one_add_norm integrable_one_add_norm
 
diff --git a/Mathlib/MeasureTheory/Function/L1Space.lean b/Mathlib/MeasureTheory/Function/L1Space.lean
index 29ad3435d2a72..b1af1f90d8f07 100644
--- a/Mathlib/MeasureTheory/Function/L1Space.lean
+++ b/Mathlib/MeasureTheory/Function/L1Space.lean
@@ -107,13 +107,6 @@ def HasFiniteIntegral {_ : MeasurableSpace α} (f : α → β) (μ : Measure α
   (∫⁻ a, ‖f a‖₊ ∂μ) < ∞
 #align measure_theory.has_finite_integral MeasureTheory.HasFiniteIntegral
 
--- Porting note: TODO Delete this when leanprover/lean4#2243 is fixed.
-theorem hasFiniteIntegral_def {_ : MeasurableSpace α} (f : α → β) (μ : Measure α) :
-    HasFiniteIntegral f μ ↔ ((∫⁻ a, ‖f a‖₊ ∂μ) < ∞) :=
-  Iff.rfl
-
-attribute [eqns hasFiniteIntegral_def] HasFiniteIntegral
-
 theorem hasFiniteIntegral_iff_norm (f : α → β) :
     HasFiniteIntegral f μ ↔ (∫⁻ a, ENNReal.ofReal ‖f a‖ ∂μ) < ∞ := by
   simp only [HasFiniteIntegral, ofReal_norm_eq_coe_nnnorm]
@@ -126,7 +119,7 @@ theorem hasFiniteIntegral_iff_edist (f : α → β) :
 
 theorem hasFiniteIntegral_iff_ofReal {f : α → ℝ} (h : 0 ≤ᵐ[μ] f) :
     HasFiniteIntegral f μ ↔ (∫⁻ a, ENNReal.ofReal (f a) ∂μ) < ∞ := by
-  rw [HasFiniteIntegral, lintegral_nnnorm_eq_of_ae_nonneg h]
+  simp only [HasFiniteIntegral, lintegral_nnnorm_eq_of_ae_nonneg h]
 #align measure_theory.has_finite_integral_iff_of_real MeasureTheory.hasFiniteIntegral_iff_ofReal
 
 theorem hasFiniteIntegral_iff_ofNNReal {f : α → ℝ≥0} :
@@ -252,10 +245,7 @@ theorem hasFiniteIntegral_neg_iff {f : α → β} : HasFiniteIntegral (-f) μ 
 
 theorem HasFiniteIntegral.norm {f : α → β} (hfi : HasFiniteIntegral f μ) :
     HasFiniteIntegral (fun a => ‖f a‖) μ := by
-  have eq : (fun a => (nnnorm ‖f a‖ : ℝ≥0∞)) = fun a => (‖f a‖₊ : ℝ≥0∞) := by
-    funext
-    rw [nnnorm_norm]
-  rwa [HasFiniteIntegral, eq]
+  simpa only [HasFiniteIntegral, nnnorm_norm]
 #align measure_theory.has_finite_integral.norm MeasureTheory.HasFiniteIntegral.norm
 
 theorem hasFiniteIntegral_norm_iff (f : α → β) :
@@ -443,13 +433,6 @@ def Integrable {α} {_ : MeasurableSpace α} (f : α → β) (μ : Measure α :=
   AEStronglyMeasurable f μ ∧ HasFiniteIntegral f μ
 #align measure_theory.integrable MeasureTheory.Integrable
 
--- Porting note: TODO Delete this when leanprover/lean4#2243 is fixed.
-theorem integrable_def {α} {_ : MeasurableSpace α} (f : α → β) (μ : Measure α) :
-    Integrable f μ ↔ (AEStronglyMeasurable f μ ∧ HasFiniteIntegral f μ) :=
-  Iff.rfl
-
-attribute [eqns integrable_def] Integrable
-
 theorem memℒp_one_iff_integrable {f : α → β} : Memℒp f 1 μ ↔ Integrable f μ := by
   simp_rw [Integrable, HasFiniteIntegral, Memℒp, snorm_one_eq_lintegral_nnnorm]
 #align measure_theory.mem_ℒp_one_iff_integrable MeasureTheory.memℒp_one_iff_integrable
@@ -499,7 +482,7 @@ theorem integrable_congr {f g : α → β} (h : f =ᵐ[μ] g) : Integrable f μ
 
 theorem integrable_const_iff {c : β} : Integrable (fun _ : α => c) μ ↔ c = 0 ∨ μ univ < ∞ := by
   have : AEStronglyMeasurable (fun _ : α => c) μ := aestronglyMeasurable_const
-  rw [Integrable, and_iff_right this, hasFiniteIntegral_const_iff]
+  simp only [Integrable, and_iff_right this, hasFiniteIntegral_const_iff]
 #align measure_theory.integrable_const_iff MeasureTheory.integrable_const_iff
 
 @[simp]
@@ -1215,7 +1198,8 @@ variable {H : Type*} [NormedAddCommGroup H] {m0 : MeasurableSpace α} {μ' : Mea
 theorem Integrable.trim (hm : m ≤ m0) (hf_int : Integrable f μ') (hf : StronglyMeasurable[m] f) :
     Integrable f (μ'.trim hm) := by
   refine' ⟨hf.aestronglyMeasurable, _⟩
-  rw [HasFiniteIntegral, lintegral_trim hm _]
+  unfold HasFiniteIntegral
+  rw [lintegral_trim hm _]
   · exact hf_int.2
   · exact @StronglyMeasurable.ennnorm _ m _ _ f hf
 #align measure_theory.integrable.trim MeasureTheory.Integrable.trim
@@ -1224,7 +1208,7 @@ theorem integrable_of_integrable_trim (hm : m ≤ m0) (hf_int : Integrable f (μ
     Integrable f μ' := by
   obtain ⟨hf_meas_ae, hf⟩ := hf_int
   refine' ⟨aestronglyMeasurable_of_aestronglyMeasurable_trim hm hf_meas_ae, _⟩
-  rw [HasFiniteIntegral] at hf ⊢
+  unfold HasFiniteIntegral at hf ⊢
   rwa [lintegral_trim_ae hm _] at hf
   exact AEStronglyMeasurable.ennnorm hf_meas_ae
 #align measure_theory.integrable_of_integrable_trim MeasureTheory.integrable_of_integrable_trim
diff --git a/Mathlib/MeasureTheory/Integral/BoundedContinuousFunction.lean b/Mathlib/MeasureTheory/Integral/BoundedContinuousFunction.lean
index 26a7f44928a34..97c2b7a336f5c 100644
--- a/Mathlib/MeasureTheory/Integral/BoundedContinuousFunction.lean
+++ b/Mathlib/MeasureTheory/Integral/BoundedContinuousFunction.lean
@@ -91,7 +91,8 @@ lemma lintegral_nnnorm_le (f : X →ᵇ E) :
 
 lemma integrable [IsFiniteMeasure μ] (f : X →ᵇ E) :
     Integrable f μ := by
-  refine ⟨f.continuous.measurable.aestronglyMeasurable, (hasFiniteIntegral_def _ _).mp ?_⟩
+  refine ⟨f.continuous.measurable.aestronglyMeasurable,  ?_⟩
+  unfold HasFiniteIntegral
   calc  ∫⁻ x, ‖f x‖₊ ∂μ
     _ ≤ ‖f‖₊ * (μ Set.univ)   := f.lintegral_nnnorm_le μ
     _ < ∞                     := ENNReal.mul_lt_top ENNReal.coe_ne_top (measure_ne_top μ Set.univ)
diff --git a/Mathlib/MeasureTheory/Integral/SetIntegral.lean b/Mathlib/MeasureTheory/Integral/SetIntegral.lean
index 4e32b791cb71f..da6967fd9049b 100644
--- a/Mathlib/MeasureTheory/Integral/SetIntegral.lean
+++ b/Mathlib/MeasureTheory/Integral/SetIntegral.lean
@@ -1284,7 +1284,7 @@ theorem integral_withDensity_eq_integral_smul {f : α → ℝ≥0} (f_meas : Mea
     · exact integral_nonneg fun x => NNReal.coe_nonneg _
     · refine' ⟨f_meas.coe_nnreal_real.aemeasurable.aestronglyMeasurable, _⟩
       rw [withDensity_apply _ s_meas] at hs
-      rw [HasFiniteIntegral]
+      unfold HasFiniteIntegral
       convert hs with x
       simp only [NNReal.nnnorm_eq]
   · intro u u' _ u_int u'_int h h'
diff --git a/Mathlib/Probability/Density.lean b/Mathlib/Probability/Density.lean
index 5dbe67cfb73df..5b011f65871f3 100644
--- a/Mathlib/Probability/Density.lean
+++ b/Mathlib/Probability/Density.lean
@@ -326,7 +326,7 @@ theorem integral_mul_eq_integral [HasPDF X ℙ] : ∫ x, x * (pdf X ℙ volume x
 theorem hasFiniteIntegral_mul {f : ℝ → ℝ} {g : ℝ → ℝ≥0∞} (hg : pdf X ℙ =ᵐ[volume] g)
     (hgi : ∫⁻ x, ‖f x‖₊ * g x ≠ ∞) :
     HasFiniteIntegral fun x => f x * (pdf X ℙ volume x).toReal := by
-  rw [HasFiniteIntegral]
+  unfold HasFiniteIntegral
   have : (fun x => ↑‖f x‖₊ * g x) =ᵐ[volume] fun x => ‖f x * (pdf X ℙ volume x).toReal‖₊ := by
     refine' ae_eq_trans (Filter.EventuallyEq.mul (ae_eq_refl fun x => (‖f x‖₊ : ℝ≥0∞))
       (ae_eq_trans hg.symm ofReal_toReal_ae_eq.symm)) _
diff --git a/Mathlib/Probability/Kernel/CondDistrib.lean b/Mathlib/Probability/Kernel/CondDistrib.lean
index 3cbd488e58506..30f73cc7ab144 100644
--- a/Mathlib/Probability/Kernel/CondDistrib.lean
+++ b/Mathlib/Probability/Kernel/CondDistrib.lean
@@ -322,7 +322,8 @@ theorem _root_.MeasureTheory.Integrable.comp_snd_map_prod_mk
   by_cases hX : AEMeasurable X μ
   · have hf := hf_int.1.comp_snd_map_prod_mk X (mΩ := mΩ) (mβ := mβ)
     refine' ⟨hf, _⟩
-    rw [HasFiniteIntegral, lintegral_map' hf.ennnorm (hX.prod_mk aemeasurable_id)]
+    unfold HasFiniteIntegral
+    rw [lintegral_map' hf.ennnorm (hX.prod_mk aemeasurable_id)]
     exact hf_int.2
   · rw [Measure.map_of_not_aemeasurable]
     · simp