diff --git a/Makefile b/Makefile
index e0d3913..e160a49 100644
--- a/Makefile
+++ b/Makefile
@@ -19,6 +19,7 @@ ESMJSDEPS=$(shell cat misc/mjs.lst)
 
 ULIB=$(shell echo $(LIB) | tr a-z A-Z)
 DEPS=$(sort $(wildcard bits/*.js))
+TSBITS=$(patsubst modules/%,bits/%,$(wildcard modules/[0-9][0-9]_*.js))
 TARGET=$(LIB).js
 FLOWTARGET=$(LIB).flow.js
 FLOWAUX=$(patsubst %.js,%.flow.js,$(AUXTARGETS))
@@ -53,7 +54,7 @@ bits/01_version.js: package.json
 bits/18_cfb.js: node_modules/cfb/xlscfb.flow.js
 	cp $^ $@
 
-bits/83_numbers.js: modules/83_numbers.js
+$(TSBITS): bits/%: modules/%
 	cp $^ $@
 
 
diff --git a/bits/04_base64.js b/bits/04_base64.js
index a334d48..bf9ca0f 100644
--- a/bits/04_base64.js
+++ b/bits/04_base64.js
@@ -1,44 +1,47 @@
-var Base64 = (function make_b64(){
-	var map = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
-	return {
-		encode: function(input/*:string*/)/*:string*/ {
-			var o = "";
-			var c1=0, c2=0, c3=0, e1=0, e2=0, e3=0, e4=0;
-			for(var i = 0; i < input.length; ) {
-				c1 = input.charCodeAt(i++);
-				e1 = (c1 >> 2);
-
-				c2 = input.charCodeAt(i++);
-				e2 = ((c1 & 3) << 4) | (c2 >> 4);
-
-				c3 = input.charCodeAt(i++);
-				e3 = ((c2 & 15) << 2) | (c3 >> 6);
-				e4 = (c3 & 63);
-				if (isNaN(c2)) { e3 = e4 = 64; }
-				else if (isNaN(c3)) { e4 = 64; }
-				o += map.charAt(e1) + map.charAt(e2) + map.charAt(e3) + map.charAt(e4);
-			}
-			return o;
-		},
-		decode: function b64_decode(input/*:string*/)/*:string*/ {
-			var o = "";
-			var c1=0, c2=0, c3=0, e1=0, e2=0, e3=0, e4=0;
-			input = input.replace(/[^\w\+\/\=]/g, "");
-			for(var i = 0; i < input.length;) {
-				e1 = map.indexOf(input.charAt(i++));
-				e2 = map.indexOf(input.charAt(i++));
-				c1 = (e1 << 2) | (e2 >> 4);
-				o += String.fromCharCode(c1);
-
-				e3 = map.indexOf(input.charAt(i++));
-				c2 = ((e2 & 15) << 4) | (e3 >> 2);
-				if (e3 !== 64) { o += String.fromCharCode(c2); }
-
-				e4 = map.indexOf(input.charAt(i++));
-				c3 = ((e3 & 3) << 6) | e4;
-				if (e4 !== 64) { o += String.fromCharCode(c3); }
-			}
-			return o;
-		}
-	};
-})();
+var Base64 = function() {
+  var map = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
+  return {
+    encode: function(input) {
+      var o = "";
+      var c1 = 0, c2 = 0, c3 = 0, e1 = 0, e2 = 0, e3 = 0, e4 = 0;
+      for (var i = 0; i < input.length; ) {
+        c1 = input.charCodeAt(i++);
+        e1 = c1 >> 2;
+        c2 = input.charCodeAt(i++);
+        e2 = (c1 & 3) << 4 | c2 >> 4;
+        c3 = input.charCodeAt(i++);
+        e3 = (c2 & 15) << 2 | c3 >> 6;
+        e4 = c3 & 63;
+        if (isNaN(c2)) {
+          e3 = e4 = 64;
+        } else if (isNaN(c3)) {
+          e4 = 64;
+        }
+        o += map.charAt(e1) + map.charAt(e2) + map.charAt(e3) + map.charAt(e4);
+      }
+      return o;
+    },
+    decode: function(input) {
+      var o = "";
+      var c1 = 0, c2 = 0, c3 = 0, e1 = 0, e2 = 0, e3 = 0, e4 = 0;
+      input = input.replace(/[^\w\+\/\=]/g, "");
+      for (var i = 0; i < input.length; ) {
+        e1 = map.indexOf(input.charAt(i++));
+        e2 = map.indexOf(input.charAt(i++));
+        c1 = e1 << 2 | e2 >> 4;
+        o += String.fromCharCode(c1);
+        e3 = map.indexOf(input.charAt(i++));
+        c2 = (e2 & 15) << 4 | e3 >> 2;
+        if (e3 !== 64) {
+          o += String.fromCharCode(c2);
+        }
+        e4 = map.indexOf(input.charAt(i++));
+        c3 = (e3 & 3) << 6 | e4;
+        if (e4 !== 64) {
+          o += String.fromCharCode(c3);
+        }
+      }
+      return o;
+    }
+  };
+}();
diff --git a/modules/04_base64.js b/modules/04_base64.js
new file mode 100644
index 0000000..bf9ca0f
--- /dev/null
+++ b/modules/04_base64.js
@@ -0,0 +1,47 @@
+var Base64 = function() {
+  var map = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
+  return {
+    encode: function(input) {
+      var o = "";
+      var c1 = 0, c2 = 0, c3 = 0, e1 = 0, e2 = 0, e3 = 0, e4 = 0;
+      for (var i = 0; i < input.length; ) {
+        c1 = input.charCodeAt(i++);
+        e1 = c1 >> 2;
+        c2 = input.charCodeAt(i++);
+        e2 = (c1 & 3) << 4 | c2 >> 4;
+        c3 = input.charCodeAt(i++);
+        e3 = (c2 & 15) << 2 | c3 >> 6;
+        e4 = c3 & 63;
+        if (isNaN(c2)) {
+          e3 = e4 = 64;
+        } else if (isNaN(c3)) {
+          e4 = 64;
+        }
+        o += map.charAt(e1) + map.charAt(e2) + map.charAt(e3) + map.charAt(e4);
+      }
+      return o;
+    },
+    decode: function(input) {
+      var o = "";
+      var c1 = 0, c2 = 0, c3 = 0, e1 = 0, e2 = 0, e3 = 0, e4 = 0;
+      input = input.replace(/[^\w\+\/\=]/g, "");
+      for (var i = 0; i < input.length; ) {
+        e1 = map.indexOf(input.charAt(i++));
+        e2 = map.indexOf(input.charAt(i++));
+        c1 = e1 << 2 | e2 >> 4;
+        o += String.fromCharCode(c1);
+        e3 = map.indexOf(input.charAt(i++));
+        c2 = (e2 & 15) << 4 | e3 >> 2;
+        if (e3 !== 64) {
+          o += String.fromCharCode(c2);
+        }
+        e4 = map.indexOf(input.charAt(i++));
+        c3 = (e3 & 3) << 6 | e4;
+        if (e4 !== 64) {
+          o += String.fromCharCode(c3);
+        }
+      }
+      return o;
+    }
+  };
+}();
diff --git a/modules/04_base64.ts b/modules/04_base64.ts
new file mode 100644
index 0000000..61e1b47
--- /dev/null
+++ b/modules/04_base64.ts
@@ -0,0 +1,44 @@
+var Base64 = (() => {
+	var map = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
+	return {
+		encode: function(input: string): string {
+			var o = "";
+			var c1=0, c2=0, c3=0, e1=0, e2=0, e3=0, e4=0;
+			for(var i = 0; i < input.length; ) {
+				c1 = input.charCodeAt(i++);
+				e1 = (c1 >> 2);
+
+				c2 = input.charCodeAt(i++);
+				e2 = ((c1 & 3) << 4) | (c2 >> 4);
+
+				c3 = input.charCodeAt(i++);
+				e3 = ((c2 & 15) << 2) | (c3 >> 6);
+				e4 = (c3 & 63);
+				if (isNaN(c2)) { e3 = e4 = 64; }
+				else if (isNaN(c3)) { e4 = 64; }
+				o += map.charAt(e1) + map.charAt(e2) + map.charAt(e3) + map.charAt(e4);
+			}
+			return o;
+		},
+		decode: function(input: string): string {
+			var o = "";
+			var c1=0, c2=0, c3=0, e1=0, e2=0, e3=0, e4=0;
+			input = input.replace(/[^\w\+\/\=]/g, "");
+			for(var i = 0; i < input.length;) {
+				e1 = map.indexOf(input.charAt(i++));
+				e2 = map.indexOf(input.charAt(i++));
+				c1 = (e1 << 2) | (e2 >> 4);
+				o += String.fromCharCode(c1);
+
+				e3 = map.indexOf(input.charAt(i++));
+				c2 = ((e2 & 15) << 4) | (e3 >> 2);
+				if (e3 !== 64) { o += String.fromCharCode(c2); }
+
+				e4 = map.indexOf(input.charAt(i++));
+				c3 = ((e3 & 3) << 6) | e4;
+				if (e4 !== 64) { o += String.fromCharCode(c3); }
+			}
+			return o;
+		}
+	};
+})();
diff --git a/modules/Makefile b/modules/Makefile
index eb9cba2..52a0cf4 100644
--- a/modules/Makefile
+++ b/modules/Makefile
@@ -5,6 +5,9 @@ ENTRIES=$(subst .ts,.js,$(TSFILES))
 .PHONY: all
 all: $(ENTRIES)
 
+04_base64.js: 04_base64.ts $(LIBFILES)
+	npx esbuild $< --outfile=$@ --platform=browser --target=es5
+
 83_numbers.js: 83_numbers.ts $(LIBFILES)
 	npx esbuild $< --bundle --outfile=$@ --platform=browser --format=iife --global-name=NUMBERS --target=es5