diff --git a/CHANGELOG.md b/CHANGELOG.md
index fcdbae6871..1b78fd2ddc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 BUG FIXES:
 
 * Fix crash in tofu test when using deprecated outputs ([#3249](https://github.com/opentofu/opentofu/pull/3249))
+* Fix missing provider functions when parentheses are used ([#3402](https://github.com/opentofu/opentofu/pull/3402))
 
 ## 1.10.6
 
diff --git a/go.mod b/go.mod
index ab6ea982d0..566c506f8b 100644
--- a/go.mod
+++ b/go.mod
@@ -277,4 +277,4 @@ require (
 
 go 1.24.6
 
-replace github.com/hashicorp/hcl/v2 v2.20.1 => github.com/opentofu/hcl/v2 v2.20.2-0.20250121132637-504036cd70e7
+replace github.com/hashicorp/hcl/v2 v2.20.1 => github.com/opentofu/hcl/v2 v2.20.2-0.20251021132045-587d123c2828
diff --git a/go.sum b/go.sum
index e436f18d40..4a64456936 100644
--- a/go.sum
+++ b/go.sum
@@ -926,8 +926,8 @@ github.com/opencontainers/go-digest v1.0.0 h1:apOUWs51W5PlhuyGyz9FCeeBIOUDA/6nW8
 github.com/opencontainers/go-digest v1.0.0/go.mod h1:0JzlMkj0TRzQZfJkVvzbP0HBR3IKzErnv2BNG4W4MAM=
 github.com/opencontainers/image-spec v1.1.0 h1:8SG7/vwALn54lVB/0yZ/MMwhFrPYtpEHQb2IpWsCzug=
 github.com/opencontainers/image-spec v1.1.0/go.mod h1:W4s4sFTMaBeK1BQLXbG4AdM2szdn85PY75RI83NrTrM=
-github.com/opentofu/hcl/v2 v2.20.2-0.20250121132637-504036cd70e7 h1:QHUIrylb/q3pQdQcnAr74cGWsXS1lmA8GqP+RWFMK6U=
-github.com/opentofu/hcl/v2 v2.20.2-0.20250121132637-504036cd70e7/go.mod h1:k+HgkLpoWu9OS81sy4j1XKDXaWm/rLysG33v5ibdDnc=
+github.com/opentofu/hcl/v2 v2.20.2-0.20251021132045-587d123c2828 h1:r2WiJxljn/Cxwpq9zMZ5HomJcNwmGNjKmeZnFsxkpBg=
+github.com/opentofu/hcl/v2 v2.20.2-0.20251021132045-587d123c2828/go.mod h1:k+HgkLpoWu9OS81sy4j1XKDXaWm/rLysG33v5ibdDnc=
 github.com/opentofu/registry-address v0.0.0-20230920144404-f1e51167f633 h1:81TBkM/XGIFlVvyabp0CJl00UHeVUiQjz0fddLMi848=
 github.com/opentofu/registry-address v0.0.0-20230920144404-f1e51167f633/go.mod h1:HzQhpVo/NJnGmN+7FPECCVCA5ijU7AUcvf39enBKYOc=
 github.com/packer-community/winrmcp v0.0.0-20180921211025-c76d91c1e7db h1:9uViuKtx1jrlXLBW/pMnhOfzn3iSEdLase/But/IZRU=
diff --git a/internal/lang/functions.go b/internal/lang/functions.go
index 7ad69d0078..57f500c228 100644
--- a/internal/lang/functions.go
+++ b/internal/lang/functions.go
@@ -25,7 +25,8 @@ var impureFunctions = []string{
 	"uuid",
 }
 
-// This should probably be replaced with addrs.Function everywhere
+// CoreNamespace defines the string prefix used for all core namespaced functions
+// TODO: This should probably be replaced with addrs.Function everywhere
 const CoreNamespace = addrs.FunctionNamespaceCore + "::"
 
 // Functions returns the set of functions that should be used to when evaluating
diff --git a/internal/lang/references_test.go b/internal/lang/references_test.go
new file mode 100644
index 0000000000..8b87cdf97a
--- /dev/null
+++ b/internal/lang/references_test.go
@@ -0,0 +1,102 @@
+// Copyright (c) The OpenTofu Authors
+// SPDX-License-Identifier: MPL-2.0
+// Copyright (c) 2023 HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package lang
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
+
+	"github.com/opentofu/opentofu/internal/addrs"
+)
+
+func TestReferencesInExpr(t *testing.T) {
+	// Note for developers, this list is non-exhaustive right now
+	// and there are many more expression types. This test is mainly to ensure that provider
+	// defined function references are returned from references with parentheses
+	// to resolve issue opentofu/opentofu#3401
+	tests := map[string]struct {
+		exprSrc      string
+		wantFuncRefs []string // List of expected provider function references
+	}{
+		"no functions": {
+			exprSrc:      `"literal"`,
+			wantFuncRefs: nil,
+		},
+		"provider function without parentheses": {
+			exprSrc:      `provider::testing::echo("hello")`,
+			wantFuncRefs: []string{"provider::testing::echo"},
+		},
+		"provider function with parentheses": {
+			exprSrc:      `(provider::testing::echo("hello"))`,
+			wantFuncRefs: []string{"provider::testing::echo"},
+		},
+		"provider function in binary expression": {
+			exprSrc:      `(provider::testing::add(1, 2)) + 3`,
+			wantFuncRefs: []string{"provider::testing::add"},
+		},
+		"nested parentheses": {
+			exprSrc:      `((provider::testing::echo("hello")))`,
+			wantFuncRefs: []string{"provider::testing::echo"},
+		},
+		"provider function in conditional true": {
+			exprSrc:      `true ? provider::testing::echo("yes") : "no"`,
+			wantFuncRefs: []string{"provider::testing::echo"},
+		},
+		"provider function in conditional false": {
+			exprSrc:      `false ? "yes" : provider::testing::echo("no")`,
+			wantFuncRefs: []string{"provider::testing::echo"},
+		},
+		"provider function in conditional condition": {
+			exprSrc:      `provider::testing::is_true() ? "yes" : "no"`,
+			wantFuncRefs: []string{"provider::testing::is_true"},
+		},
+		"multiple provider functions": {
+			exprSrc:      `(provider::testing::add(1, 2)) + (provider::testing::mul(3, 4))`,
+			wantFuncRefs: []string{"provider::testing::add", "provider::testing::mul"},
+		},
+		"provider function with alias": {
+			exprSrc:      `(provider::testing::custom::echo("hello"))`,
+			wantFuncRefs: []string{"provider::testing::custom::echo"},
+		},
+		"core function not included": {
+			exprSrc:      `(core::max(1, 2))`,
+			wantFuncRefs: nil, // core functions are not provider functions
+		},
+		"builtin function not included": {
+			exprSrc:      `(length([1, 2, 3]))`,
+			wantFuncRefs: nil, // builtin functions are not provider functions
+		},
+	}
+
+	for name, test := range tests {
+		t.Run(name, func(t *testing.T) {
+			expr, diags := hclsyntax.ParseExpression([]byte(test.exprSrc), "test.tf", hcl.Pos{Line: 1, Column: 1})
+			if diags.HasErrors() {
+				t.Fatalf("Failed to parse expression: %s", diags.Error())
+			}
+
+			refs, refDiags := ReferencesInExpr(addrs.ParseRef, expr)
+			if refDiags.HasErrors() {
+				t.Errorf("Unexpected diagnostics: %s", refDiags.Err())
+			}
+
+			// Extract provider function references
+			var gotFuncRefs []string
+			for _, ref := range refs {
+				if provFunc, ok := ref.Subject.(addrs.ProviderFunction); ok {
+					gotFuncRefs = append(gotFuncRefs, provFunc.String())
+				}
+			}
+
+			if diff := cmp.Diff(test.wantFuncRefs, gotFuncRefs); diff != "" {
+				t.Errorf("Wrong provider function references (-want +got):\n%s", diff)
+			}
+		})
+	}
+}