diff --git a/Lex/PPExpressions.cpp b/Lex/PPExpressions.cpp
index f43243e..590c0ee 100644
--- a/Lex/PPExpressions.cpp
+++ b/Lex/PPExpressions.cpp
@@ -161,7 +161,7 @@
     if (Literal.hadError)
       return true; // a diagnostic was already reported.
     
-    if (Literal.isFloatingLiteral()) {
+    if (Literal.isFloatingLiteral() || Literal.isImaginary) {
       PP.Diag(PeekTok, diag::err_pp_illegal_floating_literal);
       return true;
     }