diff --git a/proto/classpaths.proto b/proto/classpaths.proto
index fef62d2..829c14c 100644
--- a/proto/classpaths.proto
+++ b/proto/classpaths.proto
@@ -36,16 +36,14 @@ message Jar {
   // Minimum API level required for the jar to be included on the classpath.
   // If the system's API level is lower than the value specified in this
   // attribute, the jar will not be included in the classpath.
-  // Not setting this attribute, defaults the value to zero and implies the jar
-  // can be used on all API levels.
-  int32 min_sdk_version = 3;
+  // Not setting this attribute implies the jar can be used on all API levels.
+  string min_sdk_version = 3;
 
   // Maximum API level that the jar file supports.
-  // Not setting this attribute implies unbound maximum; otherwise set value
-  // must be greater or equal to min_sdk value.
   // If the system's API level is higher than the value specified in this
   // attribute, the jar will not be included in the classpath.
-  int32 max_sdk_version = 4;
+  // Not setting this attribute implies unbound maximum.
+  string max_sdk_version = 4;
 }
 
 // Jars exported by a single partition.