Index: src/OFMutableDictionary.m
==================================================================
--- src/OFMutableDictionary.m
+++ src/OFMutableDictionary.m
@@ -27,20 +27,23 @@
 	size_t fill = count * 4 / *size;
 	size_t newsize;
 	struct of_dictionary_bucket *newdata;
 	uint32_t i;
 
-	if (fill > 3) {
-		if (*size > SIZE_MAX / 8)
-			@throw [OFOutOfRangeException newWithClass: isa];
+	if (count > SIZE_MAX / 4)
+		@throw [OFOutOfRangeException newWithClass: isa];
 
+	if (fill > 3)
 		newsize = *size << 1;
-	} else if (fill < 1)
+	else if (fill < 1)
 		newsize = *size >> 1;
 	else
 		return;
 
+	if (newsize == 0)
+		@throw [OFOutOfRangeException newWithClass: isa];
+
 	newdata = [self allocMemoryForNItems: newsize
 				    withSize: BUCKET_SIZE];
 	memset(newdata, 0, newsize * BUCKET_SIZE);
 
 	for (i = 0; i < *size; i++) {