diff --git a/layout/svg/SVGContainerFrame.cpp b/layout/svg/SVGContainerFrame.cpp
index ffc259aa4162..633f1f29419b 100644
--- a/layout/svg/SVGContainerFrame.cpp
+++ b/layout/svg/SVGContainerFrame.cpp
@@ -104,10 +104,10 @@ void SVGContainerFrame::ReflowSVGNonDisplayText(nsIFrame* aContainer) {
   if (!aContainer->HasAnyStateBits(NS_FRAME_IS_DIRTY)) {
     return;
   }
-  NS_ASSERTION(aContainer->HasAnyStateBits(NS_FRAME_IS_NONDISPLAY) ||
-                   !aContainer->IsFrameOfType(nsIFrame::eSVG),
-               "it is wasteful to call ReflowSVGNonDisplayText on a container "
-               "frame that is not NS_FRAME_IS_NONDISPLAY");
+  MOZ_ASSERT(aContainer->HasAnyStateBits(NS_FRAME_IS_NONDISPLAY) ||
+                 !aContainer->IsFrameOfType(nsIFrame::eSVG),
+             "it is wasteful to call ReflowSVGNonDisplayText on a container "
+             "frame that is not NS_FRAME_IS_NONDISPLAY or not SVG");
   for (nsIFrame* kid : aContainer->PrincipalChildList()) {
     LayoutFrameType type = kid->Type();
     if (type == LayoutFrameType::SVGText) {
@@ -326,8 +326,10 @@ void SVGDisplayContainerFrame::ReflowSVG() {
       // Inside a non-display container frame, we might have some
       // SVGTextFrames.  We need to cause those to get reflowed in
       // case they are the target of a rendering observer.
-      NS_ASSERTION(kid->HasAnyStateBits(NS_FRAME_IS_NONDISPLAY),
-                   "expected kid to be a NS_FRAME_IS_NONDISPLAY frame");
+      MOZ_ASSERT(
+          kid->HasAnyStateBits(NS_FRAME_IS_NONDISPLAY) ||
+              !kid->IsFrameOfType(nsIFrame::eSVG),
+          "expected kid to be a NS_FRAME_IS_NONDISPLAY frame or not SVG");
       if (kid->HasAnyStateBits(NS_FRAME_IS_DIRTY)) {
         SVGContainerFrame* container = do_QueryFrame(kid);
         if (container && container->GetContent()->IsSVGElement()) {
diff --git a/layout/svg/SVGSwitchFrame.cpp b/layout/svg/SVGSwitchFrame.cpp
index 5afaddd1d461..96609075652b 100644
--- a/layout/svg/SVGSwitchFrame.cpp
+++ b/layout/svg/SVGSwitchFrame.cpp
@@ -233,7 +233,8 @@ void SVGSwitchFrame::ReflowSVG() {
     // frame list, and we're iterating over that list now anyway.
     ConsiderChildOverflow(overflowRects, child);
   } else if (child && shouldReflowSVGTextFrameInside(child)) {
-    MOZ_ASSERT(child->HasAnyStateBits(NS_FRAME_IS_NONDISPLAY),
+    MOZ_ASSERT(child->HasAnyStateBits(NS_FRAME_IS_NONDISPLAY) ||
+                   !child->IsFrameOfType(nsIFrame::eSVG),
                "Check for this explicitly in the |if|, then");
     ReflowSVGNonDisplayText(child);
   }
diff --git a/layout/svg/crashtests/1671950.html b/layout/svg/crashtests/1671950.html
new file mode 100644
index 000000000000..173ace4ea9f8
--- /dev/null
+++ b/layout/svg/crashtests/1671950.html
@@ -0,0 +1,27 @@
+<html>
+<head>
+    <style>
+        * {
+            break-before: always ! important;
+        }
+    </style>
+    <script>
+      window.addEventListener('load', () => {
+        const style = document.createElement('style')
+        document.head.appendChild(style)
+        const svg_1 = document.getElementById('id_3')
+        const svg_2 = document.createElementNS('http://www.w3.org/2000/svg', 'svg')
+        const switch_0 = document.createElementNS('http://www.w3.org/2000/svg', 'switch')
+        const c_0 = document.createElementNS('http://www.w3.org/2000/svg', 'c')
+        switch_0.appendChild(c_0)
+        svg_1.appendChild(switch_0)
+        svg_2.appendChild(svg_1)
+        document.documentElement.appendChild(svg_2)
+        style.sheet.insertRule('@-moz-document url-prefix(){*,a{all:inherit', 0)
+        SpecialPowers.wrap(window).printPreview()?.close()
+      })
+    </script>
+    <svg id='id_3'></svg>
+</head>
+</html>
+
diff --git a/layout/svg/crashtests/crashtests.list b/layout/svg/crashtests/crashtests.list
index 568d8efa324e..fc9b753bc01d 100644
--- a/layout/svg/crashtests/crashtests.list
+++ b/layout/svg/crashtests/crashtests.list
@@ -235,3 +235,4 @@ load 1600855.html
 load 1601824.html
 load 1605223-1.html
 load 1609663.html
+load 1671950.html
