diff --git a/src/comp/front/ast.rs b/src/comp/front/ast.rs
index a007e76b058..cdeea241809 100644
--- a/src/comp/front/ast.rs
+++ b/src/comp/front/ast.rs
@@ -255,6 +255,7 @@ tag lit_ {
     lit_int(int);
     lit_uint(uint);
     lit_mach_int(ty_mach, int);
+    lit_float(str);
     lit_nil;
     lit_bool(bool);
 }
@@ -274,6 +275,7 @@ tag ty_ {
     ty_bool;
     ty_int;
     ty_uint;
+    ty_float;
     ty_machine(util.common.ty_mach);
     ty_char;
     ty_str;
diff --git a/src/comp/front/lexer.rs b/src/comp/front/lexer.rs
index 403558e2934..d4948503d59 100644
--- a/src/comp/front/lexer.rs
+++ b/src/comp/front/lexer.rs
@@ -1,5 +1,6 @@
 import std.io;
 import std._str;
+import std._int;
 import std.map;
 import std.map.hashmap;
 import util.common;
@@ -314,6 +315,24 @@ impure fn consume_block_comment(reader rdr) {
     be consume_any_whitespace(rdr);
 }
 
+impure fn scan_dec_digits(reader rdr) -> int {
+
+    auto c = rdr.curr();
+
+    let int accum_int = 0;
+
+    while (is_dec_digit(c) || c == '_') {
+            if (c != '_') {
+                accum_int *= 10;
+                accum_int += dec_digit_val(c);
+            }
+            rdr.bump();
+            c = rdr.curr();
+    }
+
+    ret accum_int;
+}
+
 impure fn scan_number(mutable char c, reader rdr) -> token.token {
     auto accum_int = 0;
     auto n = rdr.next();
@@ -330,9 +349,7 @@ impure fn scan_number(mutable char c, reader rdr) -> token.token {
             rdr.bump();
             c = rdr.curr();
         }
-    }
-
-    if (c == '0' && n == 'b') {
+    } else if (c == '0' && n == 'b') {
         rdr.bump();
         rdr.bump();
         c = rdr.curr();
@@ -344,16 +361,12 @@ impure fn scan_number(mutable char c, reader rdr) -> token.token {
             rdr.bump();
             c = rdr.curr();
         }
+    } else {
+        accum_int = scan_dec_digits(rdr);
     }
 
-    while (is_dec_digit(c) || c == '_') {
-        if (c != '_') {
-            accum_int *= 10;
-            accum_int += dec_digit_val(c);
-        }
-        rdr.bump();
-        c = rdr.curr();
-    }
+    c = rdr.curr();
+    n = rdr.next();
 
     if (c == 'u' || c == 'i') {
         let bool signed = (c == 'i');
@@ -405,7 +418,18 @@ impure fn scan_number(mutable char c, reader rdr) -> token.token {
             ret token.LIT_UINT(accum_int as uint);
         }
     }
-    ret token.LIT_INT(accum_int);
+    n = rdr.curr();
+    if(n == '.') {
+        // Parse a floating-point number.
+        rdr.bump();
+        auto accum_int1 = scan_dec_digits(rdr);
+        ret token.LIT_FLOAT(_int.to_str(accum_int, 10u) + "."
+                          + _int.to_str(accum_int1, 10u));
+        // FIXME: Parse exponent.
+    }
+    else {
+        ret token.LIT_INT(accum_int);
+    }
 }
 
 impure fn next_token(reader rdr) -> token.token {
diff --git a/src/comp/front/parser.rs b/src/comp/front/parser.rs
index 9d3724f9de1..f1f8a91887f 100644
--- a/src/comp/front/parser.rs
+++ b/src/comp/front/parser.rs
@@ -537,6 +537,10 @@ impure fn parse_lit(parser p) -> ast.lit {
             p.bump();
             lit = ast.lit_uint(u);
         }
+        case (token.LIT_FLOAT(?s)) {
+            p.bump();
+            lit = ast.lit_float(s);
+        }
         case (token.LIT_MACH_INT(?tm, ?i)) {
             p.bump();
             lit = ast.lit_mach_int(tm, i);
diff --git a/src/comp/front/token.rs b/src/comp/front/token.rs
index 62c6406a6b8..a1fb1cd0174 100644
--- a/src/comp/front/token.rs
+++ b/src/comp/front/token.rs
@@ -126,6 +126,7 @@ tag token {
     LIT_INT(int);
     LIT_UINT(uint);
     LIT_MACH_INT(ty_mach, int);
+    LIT_FLOAT(str);
     LIT_STR(str);
     LIT_CHAR(char);
     LIT_BOOL(bool);
@@ -295,7 +296,7 @@ fn to_str(token t) -> str {
             ret  _int.to_str(i, 10u)
                 + "_" + ty_mach_to_str(tm);
         }
-
+        case (LIT_FLOAT(?s)) { ret s; }
         case (LIT_STR(?s)) {
             // FIXME: escape.
             ret "\"" + s + "\"";
diff --git a/src/comp/middle/trans.rs b/src/comp/middle/trans.rs
index e7102413788..7be12f910be 100644
--- a/src/comp/middle/trans.rs
+++ b/src/comp/middle/trans.rs
@@ -211,6 +211,11 @@ fn T_int() -> TypeRef {
     ret T_i32();
 }
 
+fn T_float() -> TypeRef {
+    // FIXME: switch on target type.
+    ret T_f64();
+}
+
 fn T_char() -> TypeRef {
     ret T_i32();
 }
@@ -360,10 +365,6 @@ fn T_crate(type_names tn) -> TypeRef {
     ret t;
 }
 
-fn T_double() -> TypeRef {
-    ret llvm.LLVMDoubleType();
-}
-
 fn T_taskptr(type_names tn) -> TypeRef {
     ret T_ptr(T_task(tn));
 }
@@ -590,6 +591,7 @@ fn type_of_inner(@crate_ctxt cx, @ty.t t, bool boxed) -> TypeRef {
         case (ty.ty_nil) { llty = T_nil(); }
         case (ty.ty_bool) { llty = T_bool(); }
         case (ty.ty_int) { llty = T_int(); }
+        case (ty.ty_float) { llty = T_float(); }
         case (ty.ty_uint) { llty = T_int(); }
         case (ty.ty_machine(?tm)) {
             alt (tm) {
@@ -743,6 +745,10 @@ fn C_integral(int i, TypeRef t) -> ValueRef {
     ret llvm.LLVMConstIntOfString(t, _str.buf(istr(i)), 10);
 }
 
+fn C_float(str s) -> ValueRef {
+    ret llvm.LLVMConstRealOfString(T_float(), _str.buf(s));
+}
+
 fn C_nil() -> ValueRef {
     // NB: See comment above in T_void().
     ret C_integral(0, T_i1());
@@ -879,6 +885,7 @@ fn trans_upcall2(builder b, @glue_fns glues, ValueRef lltaskptr,
         llglue = glues.upcall_glues_cdecl.(n);
     }
     let vec[ValueRef] call_args = vec(llupcall);
+
     if (!pass_task) {
         call_args += vec(lltaskptr);
     }
@@ -2290,6 +2297,9 @@ fn trans_lit(@crate_ctxt cx, &ast.lit lit, &ast.ann ann) -> ValueRef {
             }
             ret C_integral(i, t);
         }
+        case(ast.lit_float(?fs)) {
+            ret C_float(fs);
+        }
         case (ast.lit_char(?c)) {
             ret C_integral(c as int, T_char());
         }
@@ -4476,6 +4486,15 @@ fn trans_log(@block_ctxt cx, @ast.expr e) -> result {
 
     auto sub = trans_expr(cx, e);
     auto e_ty = ty.expr_ty(e);
+    alt (e_ty.struct) {
+        case(ty.ty_float) {
+            auto tmp = sub.bcx.build.Alloca(T_float());
+            sub.bcx.build.Store(sub.val, tmp);
+            sub = res(sub.bcx, tmp);
+        }
+        case(_) { }
+    }
+
     alt (e_ty.struct) {
         case (ty.ty_str) {
             auto v = vp2i(sub.bcx, sub.val);
@@ -4483,6 +4502,12 @@ fn trans_log(@block_ctxt cx, @ast.expr e) -> result {
                              "upcall_log_str",
                              vec(v));
         }
+        case (ty.ty_float) {
+            auto v = vp2i(sub.bcx, sub.val);
+            ret trans_upcall(sub.bcx,
+                             "upcall_log_float",
+                             vec(v));
+        }
         case (_) {
             ret trans_upcall(sub.bcx,
                              "upcall_log_int",
@@ -6247,7 +6272,6 @@ fn trans_crate(session.session sess, @ast.crate crate, str output,
     collect_items(cx, crate);
     collect_tag_ctors(cx, crate);
     trans_constants(cx, crate);
-
     trans_mod(cx, crate.node.module);
     trans_vec_append_glue(cx);
     if (!shared) {
diff --git a/src/comp/middle/ty.rs b/src/comp/middle/ty.rs
index c6fbb5bf14d..bf525679e2b 100644
--- a/src/comp/middle/ty.rs
+++ b/src/comp/middle/ty.rs
@@ -32,6 +32,7 @@ tag sty {
     ty_nil;
     ty_bool;
     ty_int;
+    ty_float;
     ty_uint;
     ty_machine(util.common.ty_mach);
     ty_char;
@@ -162,6 +163,7 @@ fn ty_to_str(&@t typ) -> str {
         case (ty_nil)          { s += "()";                         }
         case (ty_bool)         { s += "bool";                       }
         case (ty_int)          { s += "int";                        }
+        case (ty_float)        { s += "float";                      }
         case (ty_uint)         { s += "uint";                       }
         case (ty_machine(?tm)) { s += common.ty_mach_to_str(tm);    }
         case (ty_char)         { s += "char";                       }
@@ -418,6 +420,7 @@ fn type_is_scalar(@t ty) -> bool {
         case (ty_nil) { ret true; }
         case (ty_bool) { ret true; }
         case (ty_int) { ret true; }
+        case (ty_float) { ret true; }
         case (ty_uint) { ret true; }
         case (ty_machine(_)) { ret true; }
         case (ty_char) { ret true; }
diff --git a/src/comp/middle/typeck.rs b/src/comp/middle/typeck.rs
index e4eaf2fb97a..c849483e8ad 100644
--- a/src/comp/middle/typeck.rs
+++ b/src/comp/middle/typeck.rs
@@ -1493,6 +1493,7 @@ fn check_lit(@ast.lit lit) -> @ty.t {
         case (ast.lit_str(_))           { sty = ty.ty_str;  }
         case (ast.lit_char(_))          { sty = ty.ty_char; }
         case (ast.lit_int(_))           { sty = ty.ty_int;  }
+        case (ast.lit_float(_))           { sty = ty.ty_float;  }
         case (ast.lit_uint(_))          { sty = ty.ty_uint; }
         case (ast.lit_mach_int(?tm, _)) { sty = ty.ty_machine(tm); }
         case (ast.lit_nil)              { sty = ty.ty_nil;  }
diff --git a/src/comp/pretty/pprust.rs b/src/comp/pretty/pprust.rs
index 7863f3e7b9a..0e30ced131d 100644
--- a/src/comp/pretty/pprust.rs
+++ b/src/comp/pretty/pprust.rs
@@ -283,6 +283,9 @@ impure fn print_literal(ps s, @ast.lit lit) {
     case (ast.lit_uint(?val)) { // TODO clipping? uistr?
       wrd(s, util.common.istr(val as int) + "u");
     }
+    case (ast.lit_float(?fstr)) {
+      wrd(s, fstr);
+    }
     case (ast.lit_mach_int(?mach,?val)) {
       wrd(s, util.common.istr(val as int));
       wrd(s, util.common.ty_mach_to_str(mach));
diff --git a/src/rt/rust_upcall.cpp b/src/rt/rust_upcall.cpp
index 1dba11024f4..30306104859 100644
--- a/src/rt/rust_upcall.cpp
+++ b/src/rt/rust_upcall.cpp
@@ -39,6 +39,13 @@ void upcall_log_int(rust_task *task, int32_t i) {
               "rust: %" PRId32 " (0x%" PRIx32 ")", i, i);
 }
 
+extern "C" CDECL
+void upcall_log_float(rust_task *task, double *f) {
+    LOG_UPCALL_ENTRY(task);
+    task->log(rust_log::UPCALL | rust_log::ULOG,
+              "rust: %12.12f", *f);
+}
+
 extern "C" CDECL void
 upcall_log_str(rust_task *task, rust_str *str) {
     LOG_UPCALL_ENTRY(task);