The present invention relates to a bicyclic inhibitor of the coagulation enzyme activated factor XII (FXIIa) comprising or consisting of the peptide (X1)(X2)(X3)n(X4)(X5)(X6)m(X7)(X9)l(X10)(X11)(X12)(X13)(X14)k(X15)(X16), wherein (X1) is present or absent and, if present, is an amino acid; (X2) is an amino acid with a side chain; (X3) is an amino acid and n is between 0 and 3, preferably 0 or 1 and most preferably 0; (X4) is an aliphatic L-amino acid or a cyclic L- amino acid, preferably L, P or an aromatic L-amino acid, and most preferably an aromatic L-amino acid; (X5) is an amino acid; (X6) is an amino acid and m is between 0 and 3, preferably 0 or 1 and most preferably 0; (X7) is an amino acid with a side chain; (X9) is an amino acid and I is between 0 and 3, preferably 0 or 1 and most preferably 0; (X10) is an amino acid; (X11) is an amino acid, preferably Q; (X12) is a hydrophobic L-amino acid, preferably an aliphatic L-amino acid, and is most preferably L; (X13) is an amino acid; (X14) is an amino acid and k is between 0 and 3, preferably 0 or 1 and most preferably 0, (X15) is an amino acid with a side chain; and (X18) is present or absent and, if present, is an amino acid; and wherein the side chains of (X2), (X7) and (X15) are connected via a connecting molecule, said connecting molecule having at least three functional groups, each functional group forming a covalent bond with one of the side chains of (X2), (X7) and (X15).