diff --git a/src/compile.cpp b/src/compile.cpp
index 6837e9e7b1..50e2bfb9e2 100644
--- a/src/compile.cpp
+++ b/src/compile.cpp
@@ -2590,7 +2590,7 @@ doubleToInt(int64_t a)
   double f = bitsToDouble(a);
   switch (fpclassify(f)) {
   case FP_NAN: return 0;
-  case FP_INFINITE: return isinf(f) == 1 ? INT32_MAX : INT32_MIN;
+  case FP_INFINITE: return signbit(f) ? INT32_MIN : INT32_MAX;
   default: return f >= INT32_MAX ? INT32_MAX
       : (f <= INT32_MIN ? INT32_MIN : static_cast<int32_t>(f));
   }
@@ -2602,7 +2602,7 @@ doubleToLong(int64_t a)
   double f = bitsToDouble(a);
   switch (fpclassify(f)) {
   case FP_NAN: return 0;
-  case FP_INFINITE: return isinf(f) == 1 ? INT64_MAX : INT64_MIN;
+  case FP_INFINITE: return signbit(f) ? INT64_MIN : INT64_MAX;
   default: return f >= INT64_MAX ? INT64_MAX
       : (f <= INT64_MIN ? INT64_MIN : static_cast<int64_t>(f));
   }
@@ -2750,7 +2750,7 @@ floatToInt(int32_t a)
   float f = bitsToFloat(a);
   switch (fpclassify(f)) {
   case FP_NAN: return 0;
-  case FP_INFINITE: return isinf(f) == 1 ? INT32_MAX : INT32_MIN;
+  case FP_INFINITE: return signbit(f) ? INT32_MIN : INT32_MAX;
   default: return f >= INT32_MAX ? INT32_MAX
       : (f <= INT32_MIN ? INT32_MIN : static_cast<int32_t>(f));
   }
@@ -2762,7 +2762,7 @@ floatToLong(int32_t a)
   float f = bitsToFloat(a);
   switch (fpclassify(f)) {
   case FP_NAN: return 0;
-  case FP_INFINITE: return isinf(f) == 1 ? INT64_MAX : INT64_MIN;
+  case FP_INFINITE: return signbit(f) ? INT64_MIN : INT64_MAX;
   default: return static_cast<int64_t>(f);
   }
 }
diff --git a/src/interpret.cpp b/src/interpret.cpp
index e9f715d1de..6e18a3d3e7 100644
--- a/src/interpret.cpp
+++ b/src/interpret.cpp
@@ -1081,7 +1081,7 @@ interpret3(Thread* t, const int base)
     double f = popDouble(t);
     switch (fpclassify(f)) {
     case FP_NAN: pushInt(t, 0); break;
-    case FP_INFINITE: pushInt(t, isinf(f) == 1 ? INT32_MAX : INT32_MIN); break;
+    case FP_INFINITE: pushInt(t, signbit(f) ? INT32_MIN : INT32_MAX); break;
     default: pushInt
         (t,  f >= INT32_MAX ? INT32_MAX
          : (f <= INT32_MIN ? INT32_MIN : static_cast<int32_t>(f)));
@@ -1093,8 +1093,7 @@ interpret3(Thread* t, const int base)
     double f = popDouble(t);
     switch (fpclassify(f)) {
     case FP_NAN: pushLong(t, 0); break;
-    case FP_INFINITE: pushLong(t, isinf(f) == 1 ? INT64_MAX : INT64_MIN);
-      break;
+    case FP_INFINITE: pushLong(t, signbit(f) ? INT64_MIN : INT64_MAX); break;
     default: pushLong
         (t,  f >= INT64_MAX ? INT64_MAX
          : (f <= INT64_MIN ? INT64_MIN : static_cast<int64_t>(f)));
@@ -1298,7 +1297,7 @@ interpret3(Thread* t, const int base)
     float f = popFloat(t);
     switch (fpclassify(f)) {
     case FP_NAN: pushInt(t, 0); break;
-    case FP_INFINITE: pushInt(t, isinf(f) == 1 ? INT32_MAX : INT32_MIN); break;
+    case FP_INFINITE: pushInt(t, signbit(f) ? INT32_MIN : INT32_MAX); break;
     default: pushInt(t, f >= INT32_MAX ? INT32_MAX
                      : (f <= INT32_MIN ? INT32_MIN : static_cast<int32_t>(f)));
       break;
@@ -1309,7 +1308,7 @@ interpret3(Thread* t, const int base)
     float f = popFloat(t);
     switch (fpclassify(f)) {
     case FP_NAN: pushLong(t, 0); break;
-    case FP_INFINITE: pushLong(t, isinf(f) == 1 ? INT64_MAX : INT64_MIN);
+    case FP_INFINITE: pushLong(t, signbit(f) ? INT64_MIN : INT64_MAX);
       break;
     default: pushLong(t, static_cast<int64_t>(f)); break;
     }