diff --git a/CHANGELOG.md b/CHANGELOG.md
index d8d08de9..434ef5c8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@ HEAD
 
 * Made `JsonDocument`'s destructor protected (issue #1480)
 * Added missing calls to `client.stop()` in `JsonHttpClient.ino` (issue #1485)
+* Fixed error `expected ')' before 'char'` when `isdigit()` is a macro (issue #1487)
 
 v6.17.2 (2020-11-14)
 -------
diff --git a/extras/tests/Misc/conflicts.cpp b/extras/tests/Misc/conflicts.cpp
index 5c79faf1..e809fe8a 100644
--- a/extras/tests/Misc/conflicts.cpp
+++ b/extras/tests/Misc/conflicts.cpp
@@ -39,6 +39,15 @@
 #define _max()
 #define _min()
 
+// Realtek Ameba
+#define isdigit(c) (((c) >= '0') && ((c) <= '9'))
+#define isprint(c)
+#define isxdigit(c)
+#define isspace(c)
+#define isupper(c)
+#define islower(c)
+#define isalpha(c)
+
 // issue #839
 #define BLOCKSIZE
 #define CAPACITY
diff --git a/src/ArduinoJson/Polyfills/ctype.hpp b/src/ArduinoJson/Polyfills/ctype.hpp
index bb3bc8b7..fd3683d6 100644
--- a/src/ArduinoJson/Polyfills/ctype.hpp
+++ b/src/ArduinoJson/Polyfills/ctype.hpp
@@ -8,9 +8,11 @@
 
 namespace ARDUINOJSON_NAMESPACE {
 
+#ifndef isdigit
 inline bool isdigit(char c) {
   return '0' <= c && c <= '9';
 }
+#endif
 
 inline bool issign(char c) {
   return '-' == c || c == '+';