diff --git a/tests/YGDefaultValuesTest.cpp b/tests/YGDefaultValuesTest.cpp
index dfdf7cd7..b553a011 100644
--- a/tests/YGDefaultValuesTest.cpp
+++ b/tests/YGDefaultValuesTest.cpp
@@ -27,28 +27,28 @@ TEST(YogaTest, assert_default_values) {
   ASSERT_EQ(YGOverflowVisible, YGNodeStyleGetOverflow(root));
   ASSERT_FLOAT_EQ(0, YGNodeStyleGetFlexGrow(root));
   ASSERT_FLOAT_EQ(0, YGNodeStyleGetFlexShrink(root));
-  ASSERT_FALSE(YGNodeStyleGetFlexBasis(root).isDefined);
+  ASSERT_FALSE(YGNodeStyleGetFlexBasis(root).unit != YGUnitUndefined);
 
-  ASSERT_FALSE(YGNodeStyleGetPosition(root, YGEdgeLeft).isDefined);
-  ASSERT_FALSE(YGNodeStyleGetPosition(root, YGEdgeTop).isDefined);
-  ASSERT_FALSE(YGNodeStyleGetPosition(root, YGEdgeRight).isDefined);
-  ASSERT_FALSE(YGNodeStyleGetPosition(root, YGEdgeBottom).isDefined);
-  ASSERT_FALSE(YGNodeStyleGetPosition(root, YGEdgeStart).isDefined);
-  ASSERT_FALSE(YGNodeStyleGetPosition(root, YGEdgeEnd).isDefined);
+  ASSERT_FALSE(YGNodeStyleGetPosition(root, YGEdgeLeft).unit != YGUnitUndefined);
+  ASSERT_FALSE(YGNodeStyleGetPosition(root, YGEdgeTop).unit != YGUnitUndefined);
+  ASSERT_FALSE(YGNodeStyleGetPosition(root, YGEdgeRight).unit != YGUnitUndefined);
+  ASSERT_FALSE(YGNodeStyleGetPosition(root, YGEdgeBottom).unit != YGUnitUndefined);
+  ASSERT_FALSE(YGNodeStyleGetPosition(root, YGEdgeStart).unit != YGUnitUndefined);
+  ASSERT_FALSE(YGNodeStyleGetPosition(root, YGEdgeEnd).unit != YGUnitUndefined);
 
   ASSERT_FLOAT_EQ(0, YGNodeStyleGetMargin(root, YGEdgeLeft).value);
   ASSERT_FLOAT_EQ(0, YGNodeStyleGetMargin(root, YGEdgeTop).value);
   ASSERT_FLOAT_EQ(0, YGNodeStyleGetMargin(root, YGEdgeRight).value);
   ASSERT_FLOAT_EQ(0, YGNodeStyleGetMargin(root, YGEdgeBottom).value);
-  ASSERT_FALSE(YGNodeStyleGetMargin(root, YGEdgeStart).isDefined);
-  ASSERT_FALSE(YGNodeStyleGetMargin(root, YGEdgeEnd).isDefined);
+  ASSERT_FALSE(YGNodeStyleGetMargin(root, YGEdgeStart).unit != YGUnitUndefined);
+  ASSERT_FALSE(YGNodeStyleGetMargin(root, YGEdgeEnd).unit != YGUnitUndefined);
 
   ASSERT_FLOAT_EQ(0, YGNodeStyleGetPadding(root, YGEdgeLeft).value);
   ASSERT_FLOAT_EQ(0, YGNodeStyleGetPadding(root, YGEdgeTop).value);
   ASSERT_FLOAT_EQ(0, YGNodeStyleGetPadding(root, YGEdgeRight).value);
   ASSERT_FLOAT_EQ(0, YGNodeStyleGetPadding(root, YGEdgeBottom).value);
-  ASSERT_FALSE(YGNodeStyleGetPadding(root, YGEdgeStart).isDefined);
-  ASSERT_FALSE(YGNodeStyleGetPadding(root, YGEdgeEnd).isDefined);
+  ASSERT_FALSE(YGNodeStyleGetPadding(root, YGEdgeStart).unit != YGUnitUndefined);
+  ASSERT_FALSE(YGNodeStyleGetPadding(root, YGEdgeEnd).unit != YGUnitUndefined);
 
   ASSERT_FLOAT_EQ(0, YGNodeStyleGetBorder(root, YGEdgeLeft));
   ASSERT_FLOAT_EQ(0, YGNodeStyleGetBorder(root, YGEdgeTop));
@@ -57,12 +57,12 @@ TEST(YogaTest, assert_default_values) {
   ASSERT_TRUE(YGFloatIsUndefined(YGNodeStyleGetBorder(root, YGEdgeStart)));
   ASSERT_TRUE(YGFloatIsUndefined(YGNodeStyleGetBorder(root, YGEdgeEnd)));
 
-  ASSERT_FALSE(YGNodeStyleGetWidth(root).isDefined);
-  ASSERT_FALSE(YGNodeStyleGetHeight(root).isDefined);
-  ASSERT_FALSE(YGNodeStyleGetMinWidth(root).isDefined);
-  ASSERT_FALSE(YGNodeStyleGetMinHeight(root).isDefined);
-  ASSERT_FALSE(YGNodeStyleGetMaxWidth(root).isDefined);
-  ASSERT_FALSE(YGNodeStyleGetMaxHeight(root).isDefined);
+  ASSERT_FALSE(YGNodeStyleGetWidth(root).unit != YGUnitUndefined);
+  ASSERT_FALSE(YGNodeStyleGetHeight(root).unit != YGUnitUndefined);
+  ASSERT_FALSE(YGNodeStyleGetMinWidth(root).unit != YGUnitUndefined);
+  ASSERT_FALSE(YGNodeStyleGetMinHeight(root).unit != YGUnitUndefined);
+  ASSERT_FALSE(YGNodeStyleGetMaxWidth(root).unit != YGUnitUndefined);
+  ASSERT_FALSE(YGNodeStyleGetMaxHeight(root).unit != YGUnitUndefined);
 
   ASSERT_FLOAT_EQ(0, YGNodeLayoutGetLeft(root));
   ASSERT_FLOAT_EQ(0, YGNodeLayoutGetTop(root));
diff --git a/tests/YGStyleTest.cpp b/tests/YGStyleTest.cpp
index 7e94e35c..83555edd 100644
--- a/tests/YGStyleTest.cpp
+++ b/tests/YGStyleTest.cpp
@@ -26,7 +26,7 @@ TEST(YogaTest, copy_style_modified) {
   const YGNodeRef node0 = YGNodeNew();
   ASSERT_FALSE(YGNodeIsDirty(node0));
   ASSERT_EQ(YGFlexDirectionColumn, YGNodeStyleGetFlexDirection(node0));
-  ASSERT_FALSE(YGNodeStyleGetMaxHeight(node0).isDefined);
+  ASSERT_FALSE(YGNodeStyleGetMaxHeight(node0).unit != YGUnitUndefined);
 
   const YGNodeRef node1 = YGNodeNew();
   YGNodeStyleSetFlexDirection(node1, YGFlexDirectionRow);
diff --git a/yoga/Yoga.c b/yoga/Yoga.c
index 316e77ae..b9a3c1aa 100644
--- a/yoga/Yoga.c
+++ b/yoga/Yoga.c
@@ -111,18 +111,6 @@ typedef struct YGNode {
   .unit = YGUnitUndefined		 \
 }
 
-#define YG_DEFAULT_EDGE_VALUES {    \
-  [YGEdgeLeft] = YGUndefined,       \
-  [YGEdgeTop] = YGUndefined,        \
-  [YGEdgeRight] = YGUndefined,      \
-  [YGEdgeBottom] = YGUndefined,     \
-  [YGEdgeStart] = YGUndefined,      \
-  [YGEdgeEnd] = YGUndefined,        \
-  [YGEdgeHorizontal] = YGUndefined, \
-  [YGEdgeVertical] = YGUndefined,   \
-  [YGEdgeAll] = YGUndefined,        \
-}
-
 #define YG_DEFAULT_EDGE_VALUES_UNIT {    \
   [YGEdgeLeft] = YG_UNDEFINED_VALUES,       \
   [YGEdgeTop] = YG_UNDEFINED_VALUES,        \
@@ -168,7 +156,7 @@ static YGNode gYGNodeDefaults = {
     .position = YG_DEFAULT_EDGE_VALUES_UNIT,
     .margin = YG_DEFAULT_EDGE_VALUES_UNIT,
     .padding = YG_DEFAULT_EDGE_VALUES_UNIT,
-    .border = YG_DEFAULT_EDGE_VALUES,
+    .border = YG_DEFAULT_EDGE_VALUES_UNIT,
     .aspectRatio = YGUndefined,
   },
 
@@ -968,7 +956,7 @@ static float YGNodeLeadingPosition(const YGNodeRef node, const YGFlexDirection a
   const YGValue * leadingPosition =
       YGComputedEdgeValue(node->style.position, leading[axis], &YGValueUndefined);
 
-  return !leadingPosition->unit != YGUnitUndefined ? 0.0f : YGValueResolve(leadingPosition, axisSize);
+  return leadingPosition->unit == YGUnitUndefined ? 0.0f : YGValueResolve(leadingPosition, axisSize);
 }
 
 static float YGNodeTrailingPosition(const YGNodeRef node, const YGFlexDirection axis, const float axisSize) {
@@ -983,7 +971,7 @@ static float YGNodeTrailingPosition(const YGNodeRef node, const YGFlexDirection
   const YGValue * trailingPosition =
       YGComputedEdgeValue(node->style.position, trailing[axis], &YGValueUndefined);
 
-  return !trailingPosition->unit != YGUnitUndefined ? 0.0f : YGValueResolve(trailingPosition, axisSize);
+  return trailingPosition->unit == YGUnitUndefined ? 0.0f : YGValueResolve(trailingPosition, axisSize);
 }
 
 static float YGNodeBoundAxisWithinMinAndMax(const YGNodeRef node,