Previous observations from didactic studies have indicated that Vietnamese learners of German as a foreign language often fail to realize consonantal clusters in German [1, 2, 3]. The present study investigated whether this problem occurs already at the level of perception, i.e., whether Vietnamese learners find it difficult to perceive the difference between a cluster and a single consonant. We focused on the discrimination between the German cluster /ʃt/ and the single consonants /t/ and /ʃ/, both in onset and coda position. Due to different phonotactic restrictions on coda consonants in Vietnamese, we expected the coda position to pose a bigger challenge for correct discrimination than the onset position. With an AX discrimination task, we tested how 83 university students from Hanoi perceived these contrasts. Our findings show that only the distinction between /ʃt/-/ʃ/ in coda position posed a real challenge to our listeners. We attribute this difficulty to the weak and non-native auditory cues for the plosive in this position. For all other contrasts our participants performed surprisingly well. We propose that this is due to the influence of English as first L2 that facilitates the acquisition of phonological contrasts in German as an L3.