diff --git a/layout/svg/crashtests/842630-1.svg b/layout/svg/crashtests/842630-1.svg
new file mode 100644
index 000000000000..8d36998be677
--- /dev/null
+++ b/layout/svg/crashtests/842630-1.svg
@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg"><text dy="20 20">A<tspan style="display: none;">B</tspan></text></svg>
diff --git a/layout/svg/crashtests/crashtests.list b/layout/svg/crashtests/crashtests.list
index f5e25502aa74..a894c7fb5ecd 100644
--- a/layout/svg/crashtests/crashtests.list
+++ b/layout/svg/crashtests/crashtests.list
@@ -154,6 +154,7 @@ load 813420-1.svg
 load 841163-1.svg
 load 841812-1.svg
 load 842009-1.svg
+load 842630-1.svg
 load 842909-1.svg
 load 843072-1.svg
 load 847139-1.svg
diff --git a/layout/svg/nsSVGTextFrame2.cpp b/layout/svg/nsSVGTextFrame2.cpp
index 01de90562e20..5c981c833809 100644
--- a/layout/svg/nsSVGTextFrame2.cpp
+++ b/layout/svg/nsSVGTextFrame2.cpp
@@ -4079,10 +4079,7 @@ nsSVGTextFrame2::ResolvePositions(nsTArray<gfxPoint>& aDeltas)
 
   // Fill in unspecified positions for all remaining characters, noting
   // them as unaddressable if they are.
-  uint32_t index = it.TextElementCharIndex();
-  for (uint32_t i = 0; i < index; i++) {
-    mPositions.AppendElement(CharPosition::Unspecified(false));
-  }
+  uint32_t index = 0;
   while (it.Next()) {
     while (++index < it.TextElementCharIndex()) {
       mPositions.AppendElement(CharPosition::Unspecified(false));
@@ -4090,6 +4087,9 @@ nsSVGTextFrame2::ResolvePositions(nsTArray<gfxPoint>& aDeltas)
     mPositions.AppendElement(CharPosition::Unspecified(
                                              it.IsOriginalCharUnaddressable()));
   }
+  while (++index < it.TextElementCharIndex()) {
+    mPositions.AppendElement(CharPosition::Unspecified(false));
+  }
 
   // Recurse over the content and fill in character positions as we go.
   bool forceStartOfChunk = false;