diff --git a/ports/stm32/mpconfigport.h b/ports/stm32/mpconfigport.h
index bdceb8c532..86f65fda26 100644
--- a/ports/stm32/mpconfigport.h
+++ b/ports/stm32/mpconfigport.h
@@ -365,13 +365,5 @@ static inline mp_uint_t disable_irq(void) {
 // We need an implementation of the log2 function which is not a macro
 #define MP_NEED_LOG2 (1)
 
-// There is no classical C heap in bare-metal ports, only Python
-// garbage-collected heap. For completeness, emulate C heap via
-// GC heap. Note that MicroPython core never uses malloc() and friends,
-// so these defines are mostly to help extension module writers.
-#define malloc(n) m_malloc(n)
-#define free(p) m_free(p)
-#define realloc(p, n) m_realloc(p, n)
-
 // We need to provide a declaration/definition of alloca()
 #include <alloca.h>