diff --git a/include/ap_fixed_ref.h b/include/ap_fixed_ref.h
index b968e4a..0fe5220 100644
--- a/include/ap_fixed_ref.h
+++ b/include/ap_fixed_ref.h
@@ -285,7 +285,9 @@ struct af_range_ref {
   ASSIGN_CTYPE_TO_AF_RANGE(unsigned long)
   ASSIGN_CTYPE_TO_AF_RANGE(ap_slong)
   ASSIGN_CTYPE_TO_AF_RANGE(ap_ulong)
+#if _AP_ENABLE_HALF_ == 1
   ASSIGN_CTYPE_TO_AF_RANGE(half)
+#endif
   ASSIGN_CTYPE_TO_AF_RANGE(float)
   ASSIGN_CTYPE_TO_AF_RANGE(double)
 #undef ASSIGN_CTYPE_TO_AF_RANGE
diff --git a/include/ap_int_ref.h b/include/ap_int_ref.h
index dec614c..a9b24ee 100644
--- a/include/ap_int_ref.h
+++ b/include/ap_int_ref.h
@@ -90,7 +90,9 @@ struct ap_concat_ref {
   ASSIGN_WITH_CTYPE(unsigned long)
   ASSIGN_WITH_CTYPE(ap_slong)
   ASSIGN_WITH_CTYPE(ap_ulong)
+#if _AP_ENABLE_HALF_ == 1
   ASSIGN_WITH_CTYPE(half)
+#endif
   ASSIGN_WITH_CTYPE(float)
   ASSIGN_WITH_CTYPE(double)
 
@@ -359,7 +361,9 @@ struct ap_range_ref {
   ASSIGN_WITH_CTYPE(unsigned long)
   ASSIGN_WITH_CTYPE(ap_slong)
   ASSIGN_WITH_CTYPE(ap_ulong)
+#if _AP_ENABLE_HALF_ == 1
   ASSIGN_WITH_CTYPE(half)
+#endif
   ASSIGN_WITH_CTYPE(float)
   ASSIGN_WITH_CTYPE(double)
 
@@ -794,7 +798,9 @@ struct ap_bit_ref {
     return *this;                                           \
   }
 
+#if _AP_ENABLE_HALF_ == 1
   ASSIGN_WITH_CTYPE_FP(half)
+#endif
   ASSIGN_WITH_CTYPE_FP(float)
   ASSIGN_WITH_CTYPE_FP(double)