diff --git a/configs/provider_requirements.go b/configs/provider_requirements.go
index 361fec5eb..74188ed81 100644
--- a/configs/provider_requirements.go
+++ b/configs/provider_requirements.go
@@ -4,6 +4,7 @@ import (
 	version "github.com/hashicorp/go-version"
 	"github.com/hashicorp/hcl/v2"
 	"github.com/hashicorp/terraform/addrs"
+	"github.com/zclconf/go-cty/cty"
 )
 
 // RequiredProvider represents a declaration of a dependency on a particular
@@ -55,41 +56,61 @@ func decodeRequiredProvidersBlock(block *hcl.Block) (*RequiredProviders, hcl.Dia
 				vc := VersionConstraint{
 					DeclRange: attr.Range,
 				}
-				constraintStr := expr.GetAttr("version").AsString()
-				constraints, err := version.NewConstraint(constraintStr)
-				if err != nil {
-					// NewConstraint doesn't return user-friendly errors, so we'll just
-					// ignore the provided error and produce our own generic one.
+				constraint := expr.GetAttr("version")
+				if !constraint.Type().Equals(cty.String) || constraint.IsNull() {
 					diags = append(diags, &hcl.Diagnostic{
 						Severity: hcl.DiagError,
 						Summary:  "Invalid version constraint",
-						Detail:   "This string does not use correct version constraint syntax.",
+						Detail:   "Version must be specified as a string.",
 						Subject:  attr.Expr.Range().Ptr(),
 					})
 				} else {
-					vc.Required = constraints
-					rp.Requirement = vc
+					constraintStr := constraint.AsString()
+					constraints, err := version.NewConstraint(constraintStr)
+					if err != nil {
+						// NewConstraint doesn't return user-friendly errors, so we'll just
+						// ignore the provided error and produce our own generic one.
+						diags = append(diags, &hcl.Diagnostic{
+							Severity: hcl.DiagError,
+							Summary:  "Invalid version constraint",
+							Detail:   "This string does not use correct version constraint syntax.",
+							Subject:  attr.Expr.Range().Ptr(),
+						})
+					} else {
+						vc.Required = constraints
+						rp.Requirement = vc
+					}
 				}
 			}
 			if expr.Type().HasAttribute("source") {
-				rp.Source = expr.GetAttr("source").AsString()
-
-				fqn, sourceDiags := addrs.ParseProviderSourceString(rp.Source)
-
-				if sourceDiags.HasErrors() {
-					hclDiags := sourceDiags.ToHCL()
-					// The diagnostics from ParseProviderSourceString don't contain
-					// source location information because it has no context to compute
-					// them from, and so we'll add those in quickly here before we
-					// return.
-					for _, diag := range hclDiags {
-						if diag.Subject == nil {
-							diag.Subject = attr.Expr.Range().Ptr()
-						}
-					}
-					diags = append(diags, hclDiags...)
+				source := expr.GetAttr("source")
+				if !source.Type().Equals(cty.String) || source.IsNull() {
+					diags = append(diags, &hcl.Diagnostic{
+						Severity: hcl.DiagError,
+						Summary:  "Invalid source",
+						Detail:   "Source must be specified as a string.",
+						Subject:  attr.Expr.Range().Ptr(),
+					})
 				} else {
-					rp.Type = fqn
+					rp.Source = source.AsString()
+
+					fqn, sourceDiags := addrs.ParseProviderSourceString(rp.Source)
+
+					if sourceDiags.HasErrors() {
+						hclDiags := sourceDiags.ToHCL()
+						// The diagnostics from ParseProviderSourceString don't contain
+						// source location information because it has no context to compute
+						// them from, and so we'll add those in quickly here before we
+						// return.
+						for _, diag := range hclDiags {
+							if diag.Subject == nil {
+								diag.Subject = attr.Expr.Range().Ptr()
+							}
+						}
+						diags = append(diags, hclDiags...)
+					} else {
+						rp.Type = fqn
+					}
 				}
 			}
 
diff --git a/configs/provider_requirements_test.go b/configs/provider_requirements_test.go
index 3d1da1a23..42e4bfbe1 100644
--- a/configs/provider_requirements_test.go
+++ b/configs/provider_requirements_test.go
@@ -306,6 +306,32 @@ func TestDecodeRequiredProvidersBlock(t *testing.T) {
 			},
 			Error: "Invalid required_providers syntax",
 		},
+		"invalid source attribute type": {
+			Block: &hcl.Block{
+				Type: "required_providers",
+				Body: hcltest.MockBody(&hcl.BodyContent{
+					Attributes: hcl.Attributes{
+						"my-test": {
+							Name: "my-test",
+							Expr: hcltest.MockExprLiteral(cty.ObjectVal(map[string]cty.Value{
+								"source": cty.DynamicVal,
+							})),
+						},
+					},
+				}),
+				DefRange: blockRange,
+			},
+			Want: &RequiredProviders{
+				RequiredProviders: map[string]*RequiredProvider{
+					"my-test": {
+						Name:      "my-test",
+						DeclRange: mockRange,
+					},
+				},
+				DeclRange: blockRange,
+			},
+			Error: "Invalid source",
+		},
 	}
 
 	for name, test := range tests {