1 files changed, 14 insertions, 2 deletions
diff --git a/src/wasm.h b/src/wasm.h
index 86bb91cc5..5a48aa3f2 100644
--- a/src/wasm.h
+++ b/src/wasm.h
@@ -166,6 +166,18 @@ struct Literal {
   Literal(float   init) : type(WasmType::f32), f32(init) {}
   Literal(double  init) : type(WasmType::f64), f64(init) {}
 
+  void printDouble(std::ostream &o, double d) {
+    const char *text = JSPrinter::numToString(d);
+    // spec interpreter hates floats starting with '.'
+    if (text[0] == '.') {
+      o << '0';
+    } else if (text[0] == '-' && text[1] == '.') {
+      o << "-0";
+      text++;
+    }
+    o << text;
+  }
+
   friend std::ostream& operator<<(std::ostream &o, Literal literal) {
     o << '(';
     prepareMinorColor(o) << printWasmType(literal.type) << ".const ";
@@ -173,8 +185,8 @@ struct Literal {
       case none: abort();
       case WasmType::i32: o << literal.i32; break;
       case WasmType::i64: o << literal.i64; break;
-      case WasmType::f32: o << JSPrinter::numToString(literal.f32); break;
-      case WasmType::f64: o << JSPrinter::numToString(literal.f64); break;
+      case WasmType::f32: literal.printDouble(o, literal.f32); break;
+      case WasmType::f64: literal.printDouble(o, literal.f64); break;
     }
     restoreNormalColor(o);
     return o << ')';