diff --git a/src/libguac/instruction.c b/src/libguac/instruction.c
index fd2d23bb..4c8dfebd 100644
--- a/src/libguac/instruction.c
+++ b/src/libguac/instruction.c
@@ -56,7 +56,10 @@ guac_instruction* guac_instruction_alloc() {
     }
 
     /* Initialize state */
+    instruction->opcode = NULL;
+    instruction->argc = 0;
     instruction->state = GUAC_INSTRUCTION_PARSE_LENGTH;
+    instruction->__elementc = 0;
 
     return instruction;