diff --git a/luprex/core/TODO b/luprex/core/TODO
index 066c0363..c7dd4297 100644
--- a/luprex/core/TODO
+++ b/luprex/core/TODO
@@ -2,10 +2,7 @@ Calling out to external servers.
 
 Support ANSI escape sequences on output.
 
-Finish documenting all builtins.
-
-Get rid of source_install_builtins after documenting all builtins.
-    - but don't forget that source_install_builtins sets the string metatable.
+Make math.random do something predictable.
 
 Do something about std::cerr && std::cout once and for all.
 
diff --git a/luprex/core/cpp/source.cpp b/luprex/core/cpp/source.cpp
index 8763b308..090e1abf 100644
--- a/luprex/core/cpp/source.cpp
+++ b/luprex/core/cpp/source.cpp
@@ -15,6 +15,7 @@
 #include <algorithm>
 #include <fstream>
 #include <iostream>
+#include <cmath>
 
 LuaDefine(makeclass, "classname", "create a class if it doesn't already exist") {
     LuaArg classname;
@@ -338,9 +339,18 @@ static eng::string source_load_lfunctions(lua_State *L) {
 
 eng::string SourceDB::rebuild() {
     lua_State *L = lua_state_;
+    LuaVar mathclass;
+    LuaStack LS(L, mathclass);
     source_clear_globals(L);
     source_load_cfunctions(L);
     eng::string errs = source_load_lfunctions(L);
+
+    // A few builtin constants.  These are hardwired.
+    LS.makeclass(mathclass, "math");
+    LS.rawset(mathclass, "pi", M_PI);
+    LS.rawset(mathclass, "huge", HUGE_VAL);
+
+    LS.result();
     return errs;
 }
 
@@ -385,20 +395,20 @@ void SourceDB::init(lua_State *L) {
     lua_state_ = L;
     LuaVar globtab, persist, unpersist, classname, classtab, funcname, funcp, rawfunc, nullstring;
     LuaStack LS(L, globtab, persist, unpersist, classname, classtab, funcname, funcp, rawfunc, nullstring);
-
-    source_clear_globals(L);
-    source_load_cfunctions(L);
+    LS.getglobaltable(globtab);
+    LS.rawset(LuaRegistry, "sourcedb", LuaNewTable);
 
     // Set the metatable for strings.
     LS.makeclass(classtab, "string");
     LS.set(nullstring, "");
     LS.setmetatable(nullstring, classtab);
 
+    // Rebuild the global environment.
+    rebuild();
+
     // We need to register all C functions with the eris permanents tables.
-    LS.getglobaltable(globtab);
     LS.rawget(persist, LuaRegistry, "persist");
     LS.rawget(unpersist, LuaRegistry, "unpersist");
-    LS.rawset(LuaRegistry, "sourcedb", LuaNewTable);
     LS.set(classname, LuaNil);
     while (LS.next(globtab, classname, classtab) != 0) {
         if (LS.isstring(classname) && LS.istable(classtab)) {