diff --git a/syscalls.h b/syscalls.h
index 573dd701..d5130f6a 100644
--- a/syscalls.h
+++ b/syscalls.h
@@ -55,33 +55,36 @@ static inline long syscall3(long syscall, long arg1, long arg2, long arg3)
 static inline long syscall4(long syscall, long arg1, long arg2, long arg3, long arg4)
 {
     unsigned long ret;
-    /* FIXME: matching constraint references invalid operand number */
-    // __asm__ __volatile__("syscall"
-    //                      : "=a"(ret)
-    //                      : "a"(syscall), "D"(arg1), "S"(arg2), "d"(arg3), "r10"(arg4)
-    //                      : "rcx", "r11", "memory");
+    register long r10 __asm__("r10") = arg4;
+    __asm__ __volatile__("syscall"
+                         : "=a"(ret)
+                         : "a"(syscall), "D"(arg1), "S"(arg2), "d"(arg3), "r"(r10)
+                         : "rcx", "r11", "memory");
     return ret;
 }
 
 static inline long syscall5(long syscall, long arg1, long arg2, long arg3, long arg4, long arg5)
 {
     unsigned long ret;
-    /* FIXME: matching constraint references invalid operand number */
-    // __asm__ __volatile__("syscall"
-    //                      : "=a"(ret)
-    //                      : "a"(syscall), "D"(arg1), "S"(arg2), "d"(arg3), "r10"(arg4), "r8"(arg5)
-    //                      : "rcx", "r11", "memory");
+    register long r10 __asm__("r10") = arg4;
+    register long r8 __asm__("r8") = arg5;
+    __asm__ __volatile__("syscall"
+                         : "=a"(ret)
+                         : "a"(syscall), "D"(arg1), "S"(arg2), "d"(arg3), "r"(r10), "r"(r8)
+                         : "rcx", "r11", "memory");
     return ret;
 }
 
 static inline long syscall6(long syscall, long arg1, long arg2, long arg3, long arg4, long arg5, long arg6)
 {
     unsigned long ret;
-    /* FIXME: matching constraint references invalid operand number */
-    // __asm__ __volatile__("syscall"
-    //                      : "=a"(ret)
-    //                      : "a"(syscall), "D"(arg1), "S"(arg2), "d"(arg3), "r10"(arg4), "r8"(arg5), "r9"(arg6)
-    //                      : "rcx", "r11", "memory");
+    register long r10 __asm__("r10") = arg4;
+    register long r8 __asm__("r8") = arg5;
+    register long r9 __asm__("r9") = arg6;
+    __asm__ __volatile__("syscall"
+                         : "=a"(ret)
+                         : "a"(syscall), "D"(arg1), "S"(arg2), "d"(arg3), "r"(r10), "r"(r8), "r"(r9)
+                         : "rcx", "r11", "memory");
     return ret;
 }