diff --git a/Project.toml b/Project.toml
index de56a2d4..e02c9509 100644
--- a/Project.toml
+++ b/Project.toml
@@ -4,6 +4,7 @@ version = "4.7.2"
 
 [deps]
 FindFirstFunctions = "64ca27bc-2ba2-4a57-88aa-44e436879224"
+ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 PrettyTables = "08abe8d2-0d0c-5749-adfa-8a2ac140af0d"
 RecipesBase = "3cdcf5f2-1ef4-517c-9805-6587b60abb01"
@@ -11,14 +12,13 @@ Reexport = "189a3867-3050-52da-a836-e630ba90ab69"
 
 [weakdeps]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
-ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 Optim = "429524aa-4258-5aef-a3af-852621145aeb"
 RegularizationTools = "29dad682-9a27-4bc3-9c72-016788665182"
 Symbolics = "0c5d862f-8b57-4792-8d23-62f2024744c7"
 
 [extensions]
 DataInterpolationsChainRulesCoreExt = "ChainRulesCore"
-DataInterpolationsOptimExt = ["ForwardDiff", "Optim"]
+DataInterpolationsOptimExt = "Optim"
 DataInterpolationsRegularizationToolsExt = "RegularizationTools"
 DataInterpolationsSymbolicsExt = "Symbolics"
 
diff --git a/src/DataInterpolations.jl b/src/DataInterpolations.jl
index 752a96a7..6453558d 100644
--- a/src/DataInterpolations.jl
+++ b/src/DataInterpolations.jl
@@ -17,6 +17,7 @@ end
 
 using LinearAlgebra, RecipesBase
 using PrettyTables
+using ForwardDiff
 import FindFirstFunctions: searchsortedfirstcorrelated, searchsortedlastcorrelated,
                            bracketstrictlymontonic