diff --git a/py/asmx86.c b/py/asmx86.c
index e4736251f8..e69d06d8bb 100644
--- a/py/asmx86.c
+++ b/py/asmx86.c
@@ -497,7 +497,7 @@ void asm_x86_push_local_addr(asm_x86_t *as, int local_num, int temp_r32)
 #endif
 
 void asm_x86_call_ind(asm_x86_t *as, size_t fun_id, mp_uint_t n_args, int temp_r32) {
-    assert(n_args <= 5);
+    assert(n_args <= 4);
 
     // Align stack on 16-byte boundary during the call
     unsigned int align = ((n_args + 3) & ~3) - n_args;
@@ -505,9 +505,6 @@ void asm_x86_call_ind(asm_x86_t *as, size_t fun_id, mp_uint_t n_args, int temp_r
         asm_x86_sub_r32_i32(as, ASM_X86_REG_ESP, align * WORD_SIZE);
     }
 
-    if (n_args > 4) {
-        asm_x86_push_r32(as, ASM_X86_REG_ARG_5);
-    }
     if (n_args > 3) {
         asm_x86_push_r32(as, ASM_X86_REG_ARG_4);
     }
diff --git a/py/asmx86.h b/py/asmx86.h
index 7ba677b2c2..abcea18030 100644
--- a/py/asmx86.h
+++ b/py/asmx86.h
@@ -60,7 +60,6 @@
 #define ASM_X86_REG_ARG_2 ASM_X86_REG_ECX
 #define ASM_X86_REG_ARG_3 ASM_X86_REG_EDX
 #define ASM_X86_REG_ARG_4 ASM_X86_REG_EBX
-#define ASM_X86_REG_ARG_5 ASM_X86_REG_ESI
 
 // condition codes, used for jcc and setcc (despite their j-name!)
 #define ASM_X86_CC_JB  (0x2) // below, unsigned
@@ -129,7 +128,6 @@ void asm_x86_call_ind(asm_x86_t* as, size_t fun_id, mp_uint_t n_args, int temp_r
 #define REG_ARG_2 ASM_X86_REG_ARG_2
 #define REG_ARG_3 ASM_X86_REG_ARG_3
 #define REG_ARG_4 ASM_X86_REG_ARG_4
-#define REG_ARG_5 ASM_X86_REG_ARG_5
 
 // caller-save, so can be used as temporaries
 #define REG_TEMP0 ASM_X86_REG_EAX