diff --git a/collects/datalog/ast.rkt b/collects/datalog/ast.rkt
index 4105270..bce5f04 100644
--- a/collects/datalog/ast.rkt
+++ b/collects/datalog/ast.rkt
@@ -1,4 +1,6 @@
-#lang racket
+#lang racket/base
+(require racket/contract
+         racket/match)
 
 (define srcloc/c
   (or/c syntax?
diff --git a/collects/datalog/eval.rkt b/collects/datalog/eval.rkt
index 5cd00f4..a2c3ade 100644
--- a/collects/datalog/eval.rkt
+++ b/collects/datalog/eval.rkt
@@ -1,5 +1,6 @@
-#lang racket
+#lang racket/base
 (require racket/list
+         racket/contract
          "ast.rkt"
          "pretty.rkt"
          "runtime.rkt")
diff --git a/collects/datalog/main.rkt b/collects/datalog/main.rkt
index 4c8161c..bfb4500 100644
--- a/collects/datalog/main.rkt
+++ b/collects/datalog/main.rkt
@@ -1,4 +1,4 @@
-#lang racket
+#lang racket/base
 (require "runtime.rkt"
          "serialize.rkt"
          "stx.rkt")
diff --git a/collects/datalog/parse.rkt b/collects/datalog/parse.rkt
index e6e58ac..cc7cc75 100644
--- a/collects/datalog/parse.rkt
+++ b/collects/datalog/parse.rkt
@@ -1,6 +1,8 @@
-#lang racket
+#lang racket/base
 (require parser-tools/lex
          parser-tools/yacc
+         racket/list
+         racket/contract
          "private/lex.rkt"
          "ast.rkt")
 
diff --git a/collects/datalog/pretty.rkt b/collects/datalog/pretty.rkt
index 23872f8..697684e 100644
--- a/collects/datalog/pretty.rkt
+++ b/collects/datalog/pretty.rkt
@@ -1,5 +1,8 @@
-#lang racket
-(require "private/pprint.rkt"
+#lang racket/base
+(require racket/match
+         racket/list
+         racket/contract
+         "private/pprint.rkt"
          "ast.rkt")
 
 (define (format-datum s)
diff --git a/collects/datalog/private/env.rkt b/collects/datalog/private/env.rkt
index e89411b..018cbc4 100644
--- a/collects/datalog/private/env.rkt
+++ b/collects/datalog/private/env.rkt
@@ -1,5 +1,7 @@
-#lang racket
-(require "../ast.rkt")
+#lang racket/base
+(require racket/contract
+         racket/list
+         "../ast.rkt")
 
 (define env/c
   (and/c hash? immutable?))
diff --git a/collects/datalog/private/lex.rkt b/collects/datalog/private/lex.rkt
index 30ded8a..bca8b74 100644
--- a/collects/datalog/private/lex.rkt
+++ b/collects/datalog/private/lex.rkt
@@ -1,4 +1,4 @@
-#lang racket
+#lang racket/base
 (require parser-tools/lex
          (prefix-in : parser-tools/lex-sre))
 
diff --git a/collects/datalog/private/pprint.rkt b/collects/datalog/private/pprint.rkt
index 92fb922..8d3051a 100644
--- a/collects/datalog/private/pprint.rkt
+++ b/collects/datalog/private/pprint.rkt
@@ -1,4 +1,5 @@
-#lang racket
+#lang racket/base
+(require racket/list)
 (provide (all-defined-out))
 
 (define (text s) s)
diff --git a/collects/datalog/private/subst.rkt b/collects/datalog/private/subst.rkt
index 9de80d2..7c96b49 100644
--- a/collects/datalog/private/subst.rkt
+++ b/collects/datalog/private/subst.rkt
@@ -1,5 +1,8 @@
-#lang racket
-(require "../ast.rkt"
+#lang racket/base
+(require racket/match
+         racket/function
+         racket/contract
+         "../ast.rkt"
          "env.rkt")
 
 (define (subst-term env t)
diff --git a/collects/datalog/private/unify.rkt b/collects/datalog/private/unify.rkt
index 10f5b37..92a5122 100644
--- a/collects/datalog/private/unify.rkt
+++ b/collects/datalog/private/unify.rkt
@@ -1,5 +1,8 @@
-#lang racket
-(require "../ast.rkt"
+#lang racket/base
+(require racket/match
+         racket/list
+         racket/contract
+         "../ast.rkt"
          "env.rkt")
 
 (define (chase env t)
diff --git a/collects/datalog/private/variant.rkt b/collects/datalog/private/variant.rkt
index e55fe34..74cb799 100644
--- a/collects/datalog/private/variant.rkt
+++ b/collects/datalog/private/variant.rkt
@@ -1,5 +1,9 @@
-#lang racket
-(require "../ast.rkt"
+#lang racket/base
+(require racket/list
+         racket/match
+         racket/contract
+         racket/dict
+         "../ast.rkt"
          "env.rkt")
 
 ; Variants
diff --git a/collects/datalog/runtime.rkt b/collects/datalog/runtime.rkt
index ac599d2..9e476e6 100644
--- a/collects/datalog/runtime.rkt
+++ b/collects/datalog/runtime.rkt
@@ -1,5 +1,9 @@
-#lang racket
-(require "ast.rkt"
+#lang racket/base
+(require racket/contract
+         racket/list
+         racket/match
+         racket/function
+         "ast.rkt"
          "private/env.rkt"
          "private/subst.rkt"
          "private/unify.rkt"
diff --git a/collects/datalog/stx.rkt b/collects/datalog/stx.rkt
index 87c480b..5f9fd10 100644
--- a/collects/datalog/stx.rkt
+++ b/collects/datalog/stx.rkt
@@ -1,4 +1,4 @@
-#lang racket
+#lang racket/base
 (require (for-syntax syntax/parse
                      racket/local
                      racket/function