diff --git a/rust.mm b/rust.mm
index 864e44e..f52d27f 100644
--- a/rust.mm
+++ b/rust.mm
@@ -939,7 +939,9 @@ OSErr calculateRuns(BBLMParamBlock &params, const BBLMCallbackBlock *callbacks)
             runStart = iter.Offset();
         }
 
-        wordchr = isalpha(ch) || isdigit(ch) || ch == '_';
+        // '.' is considered a word char to avoid the "0.0" in "tuple.0.0"
+        // being classified as a floating-point number.
+        wordchr = isalpha(ch) || isdigit(ch) || ch == '_' || ch == '.';
     }
 
     makeCodeRun(iter, runStart, *callbacks);
diff --git a/smoke.rs b/smoke.rs
index 812fe64..e2f41c7 100644
--- a/smoke.rs
+++ b/smoke.rs
@@ -85,8 +85,11 @@
   5.974e24          // lowercase e
   7.348e+22         // uppercase E and plus
 
+   .1234            // no leading zero (invalid)
+
   let tuple = ((8, 4), 48);
-  let a = tuple.0.0;
+  tuple.0
+  tuple.0.0         // tuple indexing (not really numbers)
 
 // Numeric Suffixes
 // ----------------