diff --git a/src/common.cpp b/src/common.cpp
index f3c91df30..fbee108ff 100644
--- a/src/common.cpp
+++ b/src/common.cpp
@@ -75,11 +75,20 @@ static volatile bool termsize_valid = false;
 static char *wcs2str_internal(const wchar_t *in, char *out);
 static void debug_shared(const wchar_t msg_level, const wcstring &msg);
 
-const wchar_t *whitespace = L" \t\r\n\v";
+const wcstring whitespace = L" \t\r\n\v";
 const char *whitespace_narrow = " \t\r\n\v";
 
+bool is_whitespace(const wchar_t input) {
+    for (auto c : whitespace) {
+        if (c == input) {
+            return true;
+        }
+    }
+    return false;
+}
+
 bool is_whitespace(const wcstring &input) {
-    return input.find_first_not_of(whitespace);
+    return input.find_first_not_of(whitespace) == wcstring::npos;
 }
 
 bool has_working_tty_timestamps = true;
diff --git a/src/common.h b/src/common.h
index 8047018b5..9b84f7625 100644
--- a/src/common.h
+++ b/src/common.h
@@ -206,9 +206,10 @@ extern const wchar_t *program_name;
 extern bool has_working_tty_timestamps;
 
 /// A list of all whitespace characters
-extern const wchar_t *whitespace;
+extern const wcstring whitespace;
 extern const char *whitespace_narrow;
 
+bool is_whitespace(const wchar_t input);
 bool is_whitespace(const wcstring &input);
 inline bool is_whitespace(const wchar_t *input) { return is_whitespace(wcstring(input)); }