diff --git a/content/svg/content/test/Makefile.in b/content/svg/content/test/Makefile.in
index 2ed481e8a16..ebb6b864148 100644
--- a/content/svg/content/test/Makefile.in
+++ b/content/svg/content/test/Makefile.in
@@ -68,6 +68,9 @@ _TEST_FILES = \
 		test_pointer-events.xhtml \
 		test_scientific.html \
 		scientific-helper.svg \
+		test_SVGAnimatedImageSMILDisabled.html \
+		animated-svg-image-helper.html \
+		animated-svg-image-helper.svg \
 		test_SVGLengthList.xhtml \
 		test_SVGPathSegList.xhtml \
 		test_SVGStyleElement.xhtml \
diff --git a/content/svg/content/test/animated-svg-image-helper.html b/content/svg/content/test/animated-svg-image-helper.html
new file mode 100644
index 00000000000..94af2098bce
--- /dev/null
+++ b/content/svg/content/test/animated-svg-image-helper.html
@@ -0,0 +1,3 @@
+<html>
+  <img src="animated-svg-image-helper.svg">
+</html>
diff --git a/content/svg/content/test/animated-svg-image-helper.svg b/content/svg/content/test/animated-svg-image-helper.svg
new file mode 100644
index 00000000000..5f6f564e921
--- /dev/null
+++ b/content/svg/content/test/animated-svg-image-helper.svg
@@ -0,0 +1,3 @@
+<svg xmlns="http://www.w3.org/2000/svg">
+  <set attributeName="font-size" to="50"/>
+</svg>
diff --git a/content/svg/content/test/test_SVGAnimatedImageSMILDisabled.html b/content/svg/content/test/test_SVGAnimatedImageSMILDisabled.html
new file mode 100644
index 00000000000..2a78e3c0548
--- /dev/null
+++ b/content/svg/content/test/test_SVGAnimatedImageSMILDisabled.html
@@ -0,0 +1,58 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=623945
+-->
+<head>
+  <title>Test for Bug 623945</title>
+  <script type="application/javascript" src="/MochiKit/packed.js"></script>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=623945">Mozilla Bug 623945</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 623945 **/
+/* This test makes sure we don't crash when using an animated SVG image with
+ * the 'svg.smil.enabled' pref turned off. */
+
+SimpleTest.waitForExplicitFinish();
+
+function setSMILEnabled(enabled) {
+  netscape.security.PrivilegeManager.enablePrivilege('UniversalXPConnect');
+  var prefs = Components.classes["@mozilla.org/preferences-service;1"]
+                 .getService(Components.interfaces.nsIPrefBranch);
+  prefs.setBoolPref("svg.smil.enabled", enabled);
+}
+
+function iframeLoaded() {
+  // Woo-hoo, we didn't crash! Declare success!
+  ok(true, "got through the test without crashing");
+
+  // Re-enable SMIL pref for future tests.
+  setSMILEnabled(true);
+  SimpleTest.finish();
+}
+
+function main() {
+  // First, we turn off the SMIL pref:
+  setSMILEnabled(false);
+
+  // Then, we load an HTML document with an animated SVG image.
+  var iframe = document.createElement("iframe");
+  iframe.onload = iframeLoaded;
+  iframe.src = "animated-svg-image-helper.html";
+  document.getElementById("content").appendChild(iframe);
+}
+
+main();
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/modules/libpr0n/src/SVGDocumentWrapper.cpp b/modules/libpr0n/src/SVGDocumentWrapper.cpp
index 1a4097ab7a4..481351bb6d3 100644
--- a/modules/libpr0n/src/SVGDocumentWrapper.cpp
+++ b/modules/libpr0n/src/SVGDocumentWrapper.cpp
@@ -204,7 +204,10 @@ SVGDocumentWrapper::StartAnimation()
   nsIDocument* doc = mViewer->GetDocument();
   if (doc) {
 #ifdef MOZ_SMIL
-    doc->GetAnimationController()->Resume(nsSMILTimeContainer::PAUSE_IMAGE);
+    nsSMILAnimationController* controller = doc->GetAnimationController();
+    if (controller) {
+      controller->Resume(nsSMILTimeContainer::PAUSE_IMAGE);
+    }
 #endif // MOZ_SMIL
     doc->SetImagesNeedAnimating(PR_TRUE);
   }
@@ -221,7 +224,10 @@ SVGDocumentWrapper::StopAnimation()
   nsIDocument* doc = mViewer->GetDocument();
   if (doc) {
 #ifdef MOZ_SMIL
-    doc->GetAnimationController()->Pause(nsSMILTimeContainer::PAUSE_IMAGE);
+    nsSMILAnimationController* controller = doc->GetAnimationController();
+    if (controller) {
+      controller->Pause(nsSMILTimeContainer::PAUSE_IMAGE);
+    }
 #endif // MOZ_SMIL
     doc->SetImagesNeedAnimating(PR_FALSE);
   }
