diff --git a/src/osx/utils_osx.cpp b/src/osx/utils_osx.cpp
index 47e07ba683..20983f98de 100644
--- a/src/osx/utils_osx.cpp
+++ b/src/osx/utils_osx.cpp
@@ -66,21 +66,22 @@ bool wxColourDisplay()
 // Returns depth of screen
 int wxDisplayDepth()
 {
-    int theDepth = 0;
-    
     CGDisplayModeRef currentMode = CGDisplayCopyDisplayMode(kCGDirectMainDisplay);
     CFStringRef encoding = CGDisplayModeCopyPixelEncoding(currentMode);
-    
-    if(CFStringCompare(encoding, CFSTR(IO32BitDirectPixels), kCFCompareCaseInsensitive) == kCFCompareEqualTo)
-        theDepth = 32;
-    else if(CFStringCompare(encoding, CFSTR(IO16BitDirectPixels), kCFCompareCaseInsensitive) == kCFCompareEqualTo)
-        theDepth = 16;
-    else if(CFStringCompare(encoding, CFSTR(IO8BitIndexedPixels), kCFCompareCaseInsensitive) == kCFCompareEqualTo)
-        theDepth = 8;
-    else
-        theDepth = 32; // some reasonable default
 
-    CFRelease(encoding);
+    int theDepth = 32; // some reasonable default
+    if(encoding)
+    {
+        if(CFStringCompare(encoding, CFSTR(IO32BitDirectPixels), kCFCompareCaseInsensitive) == kCFCompareEqualTo)
+            theDepth = 32;
+        else if(CFStringCompare(encoding, CFSTR(IO16BitDirectPixels), kCFCompareCaseInsensitive) == kCFCompareEqualTo)
+            theDepth = 16;
+        else if(CFStringCompare(encoding, CFSTR(IO8BitIndexedPixels), kCFCompareCaseInsensitive) == kCFCompareEqualTo)
+            theDepth = 8;
+
+        CFRelease(encoding);
+    }
+
     CGDisplayModeRelease(currentMode);
 
     return theDepth;