diff --git a/src/common/bspf.hxx b/src/common/bspf.hxx
index a5f37de17..9a7f217b0 100644
--- a/src/common/bspf.hxx
+++ b/src/common/bspf.hxx
@@ -427,7 +427,8 @@ namespace BSPF
 
   inline bool isWhiteSpace(const char c)
   {
-    return string(" ,.;:+-*&/\\'").find(c) != string::npos;
+    static constexpr string_view spaces{" ,.;:+-*&/\\'"};
+    return spaces.find(c) != string_view::npos;
   }
 } // namespace BSPF
 
diff --git a/src/emucore/FBSurface.hxx b/src/emucore/FBSurface.hxx
index ef2390cf9..b46db8485 100644
--- a/src/emucore/FBSurface.hxx
+++ b/src/emucore/FBSurface.hxx
@@ -411,7 +411,8 @@ class FBSurface
       @return       True if whitespace character
     */
     static bool isWhiteSpace(const char c) {
-      return string(" ,.;:+-*/\\'([\n").find(c) != string::npos;
+      static constexpr string_view spaces{" ,.;:+-*/\\'([\n"};
+      return spaces.find(c) != string_view::npos;
     }
 
   protected: