Mechanisms for analyzing computer instructions implementing a program in which typestate analysis is informed by concurrency analysis. The concurrency-guided typestate analysis may simulate the “worst case” scenario due to thread interleaving by transitioning a simulated state of the variable to a special state whenever the variable is not guarded by its intended guarding lock. While in the special state, the analysis may assume that the state of the simulated variable is the worst possible state with respect to processing operations that may lead to an error depending on the state of the variable. Thus, the analysis performed may assume that referencing the variable in a state-dependent operation while the simulated state of the variable is in the special state may lead to an error, and the analysis may generate a warning, accordingly. The analysis may process the computer instructions to infer which lock is intended to guard a shared variable.