diff --git a/ext/udis86/syn.c b/ext/udis86/syn.c
index 630c21f0c7..c66e2433be 100644
--- a/ext/udis86/syn.c
+++ b/ext/udis86/syn.c
@@ -23,6 +23,7 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
+#include <inttypes.h>
 #include "types.h"
 #include "decode.h"
 #include "syn.h"
@@ -137,14 +138,14 @@ ud_syn_print_addr(struct ud *u, uint64_t addr)
     name = u->sym_resolver(u, addr, &offset);
     if (name) {
       if (offset) {
-        ud_asmprintf(u, "%s%+" FMT64 "d", name, offset);
+        ud_asmprintf(u, "%s%+" PRId64, name, offset);
       } else {
         ud_asmprintf(u, "%s", name);
       }
       return;
     }
   }
-  ud_asmprintf(u, "0x%" FMT64 "x", addr);
+  ud_asmprintf(u, "0x%" PRIx64, addr);
 }
 
 
@@ -171,7 +172,7 @@ ud_syn_print_imm(struct ud* u, const struct ud_operand *op)
     default: UD_ASSERT(!"invalid offset"); v = 0; /* keep cc happy */
     }
   }
-  ud_asmprintf(u, "0x%" FMT64 "x", v);
+  ud_asmprintf(u, "0x%" PRIx64, v);
 }
 
 uint64_t
@@ -193,7 +194,7 @@ ud_syn_print_mem_disp(struct ud* u, const struct ud_operand *op, int sign)
     case 64: v = op->lval.uqword; break;
     default: UD_ASSERT(!"invalid offset"); v = 0; /* keep cc happy */
     }
-    ud_asmprintf(u, "0x%" FMT64 "x", v);
+    ud_asmprintf(u, "0x%" PRIx64, v);
   } else {
     int64_t v;
     UD_ASSERT(op->offset != 64);
@@ -206,9 +207,9 @@ ud_syn_print_mem_disp(struct ud* u, const struct ud_operand *op, int sign)
     if (op->base == UD_R_RIP) {
       ud_syn_print_addr(u, ud_syn_rip_target(u, op));
     } else if (v < 0) {
-      ud_asmprintf(u, "-0x%" FMT64 "x", -v);
+      ud_asmprintf(u, "-0x%" PRIx64, -v);
     } else if (v > 0) {
-      ud_asmprintf(u, "%s0x%" FMT64 "x", sign? "+" : "", v);
+      ud_asmprintf(u, "%s0x%" PRIx64, sign? "+" : "", v);
     }
   }
 }