diff --git a/command/013_config_upgrade.go b/command/013_config_upgrade.go
index ece077db6..997f44f77 100644
--- a/command/013_config_upgrade.go
+++ b/command/013_config_upgrade.go
@@ -164,12 +164,12 @@ func (c *ZeroThirteenUpgradeCommand) Run(args []string) int {
 
 	// Build up a list of required providers, uniquely by local name
 	requiredProviders := make(map[string]*configs.RequiredProvider)
-	var rewritePaths []string
+	rewritePaths := make(map[string]bool)
 
 	// Step 1: copy all explicit provider requirements across
 	for path, file := range files {
 		for _, rps := range file.RequiredProviders {
-			rewritePaths = append(rewritePaths, path)
+			rewritePaths[path] = true
 			for _, rp := range rps.RequiredProviders {
 				if previous, exist := requiredProviders[rp.Name]; exist {
 					diags = diags.Append(&hcl.Diagnostic{
@@ -254,18 +254,16 @@ func (c *ZeroThirteenUpgradeCommand) Run(args []string) int {
 		// Special case: if we only have one file with a required providers
 		// block, output to that file instead.
 		if len(rewritePaths) == 1 {
-			filename = rewritePaths[0]
+			for path := range rewritePaths {
+				filename = path
+				break
+			}
 		}
 
 		// Remove the output file from the list of paths we want to rewrite
 		// later. Otherwise we'd delete the required providers block after
 		// writing it.
-		for i, path := range rewritePaths {
-			if path == filename {
-				rewritePaths = append(rewritePaths[:i], rewritePaths[i+1:]...)
-				break
-			}
-		}
+		delete(rewritePaths, filename)
 
 		// Open or create the output file
 		out, openDiags := c.openOrCreateFile(filename)
@@ -456,7 +454,7 @@ func (c *ZeroThirteenUpgradeCommand) Run(args []string) int {
 
 		// After successfully writing the new configuration, remove all other
 		// required provider blocks from remaining configuration files.
-		for _, path := range rewritePaths {
+		for path := range rewritePaths {
 			// Read and parse the existing file
 			config, err := ioutil.ReadFile(path)
 			if err != nil {
diff --git a/command/testdata/013upgrade-multiple-blocks/expected/bar-baz.tf b/command/testdata/013upgrade-multiple-blocks/expected/bar-baz.tf
index 6887569dd..f2f1d69a0 100644
--- a/command/testdata/013upgrade-multiple-blocks/expected/bar-baz.tf
+++ b/command/testdata/013upgrade-multiple-blocks/expected/bar-baz.tf
@@ -1,5 +1,2 @@
 resource bar_instance a {}
 resource baz_instance b {}
-terraform {
-  required_version = "> 0.12.0"
-}
diff --git a/command/testdata/013upgrade-multiple-blocks/expected/foo.tf b/command/testdata/013upgrade-multiple-blocks/expected/foo.tf
index 5d9203723..e29e6d315 100644
--- a/command/testdata/013upgrade-multiple-blocks/expected/foo.tf
+++ b/command/testdata/013upgrade-multiple-blocks/expected/foo.tf
@@ -1 +1,4 @@
+terraform {
+  required_version = ">= 0.12"
+}
 resource foo_instance c {}
diff --git a/command/testdata/013upgrade-multiple-blocks/expected/versions.tf b/command/testdata/013upgrade-multiple-blocks/expected/versions.tf
index bcfd89046..ba49a0da7 100644
--- a/command/testdata/013upgrade-multiple-blocks/expected/versions.tf
+++ b/command/testdata/013upgrade-multiple-blocks/expected/versions.tf
@@ -1,5 +1,9 @@
 terraform {
   required_providers {
+    foo = {
+      source  = "hashicorp/foo"
+      version = "0.5"
+    }
     bar = {
       source = "registry.acme.corp/acme/bar"
     }
@@ -7,10 +11,6 @@ terraform {
       source  = "terraform-providers/baz"
       version = "~> 2.0.0"
     }
-    foo = {
-      source  = "hashicorp/foo"
-      version = "0.5"
-    }
   }
   required_version = ">= 0.13"
 }
diff --git a/command/testdata/013upgrade-multiple-blocks/input/bar-baz.tf b/command/testdata/013upgrade-multiple-blocks/input/bar-baz.tf
index d0e6fe8c6..f2f1d69a0 100644
--- a/command/testdata/013upgrade-multiple-blocks/input/bar-baz.tf
+++ b/command/testdata/013upgrade-multiple-blocks/input/bar-baz.tf
@@ -1,10 +1,2 @@
 resource bar_instance a {}
 resource baz_instance b {}
-terraform {
-  required_version = "> 0.12.0"
-  required_providers {
-    bar = {
-      source = "registry.acme.corp/acme/bar"
-    }
-  }
-}
diff --git a/command/testdata/013upgrade-multiple-blocks/input/foo.tf b/command/testdata/013upgrade-multiple-blocks/input/foo.tf
index 99aaf52a0..582cf0e2d 100644
--- a/command/testdata/013upgrade-multiple-blocks/input/foo.tf
+++ b/command/testdata/013upgrade-multiple-blocks/input/foo.tf
@@ -1,11 +1,7 @@
 terraform {
+  required_version = ">= 0.12"
   required_providers {
     baz = "~> 2.0.0"
   }
 }
-terraform {
-  required_providers {
-    foo = "0.5"
-  }
-}
 resource foo_instance c {}
diff --git a/command/testdata/013upgrade-multiple-blocks/input/versions.tf b/command/testdata/013upgrade-multiple-blocks/input/versions.tf
new file mode 100644
index 000000000..9252a15e3
--- /dev/null
+++ b/command/testdata/013upgrade-multiple-blocks/input/versions.tf
@@ -0,0 +1,12 @@
+terraform {
+  required_providers {
+    foo = "0.5"
+  }
+}
+terraform {
+  required_providers {
+    bar = {
+      source = "registry.acme.corp/acme/bar"
+    }
+  }
+}