diff --git a/interface/lapack/trtrs.c b/interface/lapack/trtrs.c
index 54fbe8394..3cc449318 100644
--- a/interface/lapack/trtrs.c
+++ b/interface/lapack/trtrs.c
@@ -95,10 +95,12 @@ int NAME(char *UPLO, char* TRANS, char* DIAG, blasint *N, blasint *NRHS, FLOAT *
   if (trans_arg == 'R') trans = 0;
   if (trans_arg == 'C') trans = 1;
 
+  TOUPPER(uplo_arg);
   uplo = -1;
   if (uplo_arg == 'U') uplo = 0;
   if (uplo_arg == 'L') uplo = 1;
 
+  TOUPPER(diag_arg);
   diag = -1;
   if (diag_arg == 'U') diag = 0;
   if (diag_arg == 'N') diag = 1;
diff --git a/interface/lapack/ztrtrs.c b/interface/lapack/ztrtrs.c
index 7f1bd9af4..ec3343393 100644
--- a/interface/lapack/ztrtrs.c
+++ b/interface/lapack/ztrtrs.c
@@ -95,10 +95,12 @@ int NAME(char *UPLO, char* TRANS, char* DIAG, blasint *N, blasint *NRHS, FLOAT *
   if (trans_arg == 'R') trans = 2;
   if (trans_arg == 'C') trans = 3;
 
+  TOUPPER(uplo_arg);
   uplo = -1;
   if (uplo_arg == 'U') uplo = 0;
   if (uplo_arg == 'L') uplo = 1;
 
+  TOUPPER(diag_arg);
   diag = -1;
   if (diag_arg == 'U') diag = 0;
   if (diag_arg == 'N') diag = 1;