diff --git a/gfx/thebes/gfxTextRun.cpp b/gfx/thebes/gfxTextRun.cpp
index e00defe16ad..dd5a41896fb 100644
--- a/gfx/thebes/gfxTextRun.cpp
+++ b/gfx/thebes/gfxTextRun.cpp
@@ -2986,16 +2986,43 @@ void gfxFontGroup::ComputeRanges(nsTArray<gfxTextRange>& aRanges,
 
     aRanges[lastRangeIndex].end = aLength;
 
-#if 0
-    // dump out font matching info
-    if (mStyle.systemFont) return;
-    for (size_t i = 0, i_end = aRanges.Length(); i < i_end; i++) {
-        const gfxTextRange& r = aRanges[i];
-        printf("fontmatch %zd:%zd font: %s (%d)\n",
-               r.start, r.end,
-               (r.font.get() ?
-                    NS_ConvertUTF16toUTF8(r.font->GetName()).get() : "<null>"),
-               r.matchType);
+#ifndef RELEASE_BUILD
+    PRLogModuleInfo *log = (mStyle.systemFont ?
+                            gfxPlatform::GetLog(eGfxLog_textrunui) :
+                            gfxPlatform::GetLog(eGfxLog_textrun));
+
+    if (MOZ_UNLIKELY(PR_LOG_TEST(log, PR_LOG_DEBUG))) {
+        nsAutoCString lang;
+        mStyle.language->ToUTF8String(lang);
+        nsAutoString families;
+        mFamilyList.ToString(families);
+
+        // collect the font matched for each range
+        nsAutoCString fontMatches;
+        for (size_t i = 0, i_end = aRanges.Length(); i < i_end; i++) {
+            char match[256];
+            const gfxTextRange& r = aRanges[i];
+            sprintf(match, " [%u:%u] %.200s (%s)",
+                    r.start, r.end,
+                    (r.font.get() ?
+                     NS_ConvertUTF16toUTF8(r.font->GetName()).get() : "<null>"),
+                    (r.matchType == gfxTextRange::kFontGroup ?
+                         "list" :
+                         (r.matchType == gfxTextRange::kPrefsFallback) ?
+                              "prefs" : "sys"));
+            fontMatches.Append(match);
+        }
+        MOZ_LOG(log, PR_LOG_DEBUG,\
+               ("(%s-fontmatching) fontgroup: [%s] default: %s lang: %s script: %d"
+                "%s\n",
+                (mStyle.systemFont ? "textrunui" : "textrun"),
+                NS_ConvertUTF16toUTF8(families).get(),
+                (mFamilyList.GetDefaultFontType() == eFamily_serif ?
+                 "serif" :
+                 (mFamilyList.GetDefaultFontType() == eFamily_sans_serif ?
+                  "sans-serif" : "none")),
+                lang.get(), aRunScript,
+                fontMatches.get()));
     }
 #endif
 }