diff --git a/src/osp/OneStepProver0.sol b/src/osp/OneStepProver0.sol
index 2d116915..421cec63 100644
--- a/src/osp/OneStepProver0.sol
+++ b/src/osp/OneStepProver0.sol
@@ -164,15 +164,25 @@ contract OneStepProver0 is IOneStepProver {
         mach.functionPc = 0;
     }
 
-    function executeCrossModuleDynamicCall(
+    function executeCrossModuleInternalCall(
         Machine memory mach,
         Module memory mod,
         Instruction calldata inst,
-        bytes calldata
+        bytes calldata proof
     ) internal pure {
         // Get the target from the stack
-        uint32 func = mach.valueStack.pop().assumeI32();
-        uint32 module = mach.valueStack.pop().assumeI32();
+        uint32 internalIndex = uint32(inst.argumentData);
+        uint32 moduleIndex = mach.valueStack.pop().assumeI32();
+        Module memory calledMod;
+
+        MerkleProof memory modProof;
+        uint256 offset = 0;
+        (calledMod, offset) = Deserialize.module(proof, offset);
+        (modProof, offset) = Deserialize.merkleProof(proof, offset);
+        require(
+            modProof.computeRootFromModule(moduleIndex, calledMod) == mach.modulesRoot,
+            "CROSS_MODULE_INTERNAL_MODULES_ROOT"
+        );
 
         // Push the return pc to the stack
         mach.valueStack.push(createReturnValue(mach));
@@ -182,8 +192,8 @@ contract OneStepProver0 is IOneStepProver {
         mach.valueStack.push(ValueLib.newI32(mod.internalsOffset));
 
         // Jump to the target
-        mach.moduleIdx = module;
-        mach.functionIdx = func;
+        mach.moduleIdx = moduleIndex;
+        mach.functionIdx = internalIndex + calledMod.internalsOffset;
         mach.functionPc = 0;
     }
 
@@ -486,8 +496,8 @@ contract OneStepProver0 is IOneStepProver {
             impl = executeCrossModuleCall;
         } else if (opcode == Instructions.CROSS_MODULE_FORWARD) {
             impl = executeCrossModuleForward;
-        } else if (opcode == Instructions.CROSS_MODULE_DYNAMIC_CALL) {
-            impl = executeCrossModuleDynamicCall;
+        } else if (opcode == Instructions.CROSS_MODULE_INTERNAL_CALL) {
+            impl = executeCrossModuleInternalCall;
         } else if (opcode == Instructions.CALLER_MODULE_INTERNAL_CALL) {
             impl = executeCallerModuleInternalCall;
         } else if (opcode == Instructions.CALL_INDIRECT) {
diff --git a/src/precompiles/ArbWasm.sol b/src/precompiles/ArbWasm.sol
index 6ae4449e..b836a55a 100644
--- a/src/precompiles/ArbWasm.sol
+++ b/src/precompiles/ArbWasm.sol
@@ -26,6 +26,14 @@ interface ArbWasm {
     // @return version the program version (0 for EVM contracts)
     function programVersion(address program) external view returns (uint16 version);
 
+    // @notice gets the uncompressed size of the program at the given address in bytes
+    // @return size the size of the program in bytes rounded up to a multiple of 512
+    function programSize(address program) external view returns (uint32 size);
+
+    // @notice gets the memory footprint of the program at the given address in pages
+    // @return footprint the memory footprint of program in pages
+    function programMemoryFootprint(address program) external view returns (uint16 footprint);
+
     // @notice gets the conversion rate between gas and ink
     // @return price the amount of ink 1 gas buys
     function inkPrice() external view returns (uint32 price);
@@ -54,6 +62,8 @@ interface ArbWasm {
     // @return gas cost paid per half kb uncompressed.
     function callScalar() external view returns (uint16 gas);
 
+    event ProgramActivated(bytes32 indexed codehash, address program, uint16 version);
+
     error ProgramNotActivated();
     error ProgramOutOfDate(uint16 version);
     error ProgramUpToDate();
diff --git a/src/state/Instructions.sol b/src/state/Instructions.sol
index 13447d63..2d04dc5c 100644
--- a/src/state/Instructions.sol
+++ b/src/state/Instructions.sol
@@ -135,7 +135,7 @@ library Instructions {
     uint16 internal constant CROSS_MODULE_CALL = 0x8009;
     uint16 internal constant CALLER_MODULE_INTERNAL_CALL = 0x800A;
     uint16 internal constant CROSS_MODULE_FORWARD = 0x800B;
-    uint16 internal constant CROSS_MODULE_DYNAMIC_CALL = 0x800C;
+    uint16 internal constant CROSS_MODULE_INTERNAL_CALL = 0x800C;
 
     uint16 internal constant GET_GLOBAL_STATE_BYTES32 = 0x8010;
     uint16 internal constant SET_GLOBAL_STATE_BYTES32 = 0x8011;