diff --git a/content/smil/nsSMILAnimationFunction.cpp b/content/smil/nsSMILAnimationFunction.cpp
index bcb43689c049..da0ba8a438ae 100644
--- a/content/smil/nsSMILAnimationFunction.cpp
+++ b/content/smil/nsSMILAnimationFunction.cpp
@@ -464,8 +464,9 @@ nsSMILAnimationFunction::InterpolateResult(const nsSMILValueArray& aValues,
   // spec says to force discrete mode.
   if (GetCalcMode() == CALC_DISCRETE || NS_FAILED(rv)) {
     if (IsToAnimation()) {
-      // Two discrete values: our base value, and the val in our array
-      aResult = (simpleProgress < 0.5f) ? aBaseValue : aValues[0];
+      // SMIL 3, 12.6.4: Since a to animation has only 1 value, a discrete to
+      // animation will simply set the to value for the simple duration.
+      aResult = aValues[0];
     } else {
       PRUint32 index = (PRUint32) floor(simpleProgress * (aValues.Length()));
       aResult = aValues[index];
diff --git a/layout/reftests/svg/smil/anim-discrete-to-1.svg b/layout/reftests/svg/smil/anim-discrete-to-1.svg
index 41a078764c33..29f8b34a9477 100644
--- a/layout/reftests/svg/smil/anim-discrete-to-1.svg
+++ b/layout/reftests/svg/smil/anim-discrete-to-1.svg
@@ -3,8 +3,8 @@
      class="reftest-wait"
      onload="setTimeAndSnapshot(0.0, true)">
   <script xlink:href="smil-util.js" type="text/javascript"/>
-  <rect x="15" y="15" width="200" height="200" fill="blue">
+  <rect x="15" y="15" width="200" height="100" fill="blue">
     <animate attributeName="height" calcMode="discrete"
-             to="100" dur="2s"/>
+             to="200" dur="2s"/>
   </rect>
 </svg>
diff --git a/layout/reftests/svg/smil/anim-discrete-to-2.svg b/layout/reftests/svg/smil/anim-discrete-to-2.svg
index e64d5d9d0fee..d163103782c4 100644
--- a/layout/reftests/svg/smil/anim-discrete-to-2.svg
+++ b/layout/reftests/svg/smil/anim-discrete-to-2.svg
@@ -3,8 +3,8 @@
      class="reftest-wait"
      onload="setTimeAndSnapshot(0.99, true)">
   <script xlink:href="smil-util.js" type="text/javascript"/>
-  <rect x="15" y="15" width="200" height="200" fill="blue">
+  <rect x="15" y="15" width="200" height="100" fill="blue">
     <animate attributeName="height" calcMode="discrete"
-             to="100" dur="2s"/>
+             to="200" dur="2s"/>
   </rect>
 </svg>
diff --git a/layout/reftests/svg/smil/anim-feTurbulence-numOctaves-01.svg b/layout/reftests/svg/smil/anim-feTurbulence-numOctaves-01.svg
index 616af9e29b22..99979499f61a 100644
--- a/layout/reftests/svg/smil/anim-feTurbulence-numOctaves-01.svg
+++ b/layout/reftests/svg/smil/anim-feTurbulence-numOctaves-01.svg
@@ -165,6 +165,7 @@
       <animate attributeName="numOctaves"
                calcMode="discrete"
                begin="0s" dur="10.1s"
+               from="1"
                to="4"
                fill="freeze"/>
     </feTurbulence>
@@ -177,6 +178,7 @@
       <animate attributeName="numOctaves"
                calcMode="discrete"
                begin="0s" dur="10s"
+               from="1"
                to="4"
                fill="freeze"/>
     </feTurbulence>
@@ -192,6 +194,7 @@
       <animate attributeName="numOctaves"
                calcMode="discrete"
                begin="0s" dur="10.1s"
+               from="4"
                to="1"
                fill="freeze"/>
     </feTurbulence>
@@ -204,6 +207,7 @@
       <animate attributeName="numOctaves"
                calcMode="discrete"
                begin="0s" dur="10s"
+               from="4"
                to="1"
                fill="freeze"/>
     </feTurbulence>
diff --git a/layout/reftests/svg/smil/anim-svg-preserveAspectRatio-01.svg b/layout/reftests/svg/smil/anim-svg-preserveAspectRatio-01.svg
index 6e96a5d3be7e..c6b43efdbe60 100644
--- a/layout/reftests/svg/smil/anim-svg-preserveAspectRatio-01.svg
+++ b/layout/reftests/svg/smil/anim-svg-preserveAspectRatio-01.svg
@@ -15,6 +15,7 @@
     <animate attributeName="preserveAspectRatio"
              calcMode="discrete"
              begin="0s" dur="2.5s"
+             from="xMidYMid meet"
              to="xMidYMid slice"
              fill="freeze"/>
     <rect width="100%" height="100%" fill="red"/>
@@ -31,6 +32,7 @@
     <animate attributeName="preserveAspectRatio"
              calcMode="discrete"
              begin="0s" dur="2s"
+             from="xMidYMid meet"
              to="xMidYMid slice"
              fill="freeze"/>
     <rect width="100%" height="100%" fill="lime"/>