diff --git a/CMakeLists.txt b/CMakeLists.txt
index eeb0bb0b8f..6a5e0a747a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -310,10 +309,17 @@ if (MAGMA_ENABLE_CUDA)
         )
     else()
         # No Position Independent Code on Windows. Compiler will complain if you add that flag.
-        target_compile_options(magma_nvcc_flags
-            INTERFACE
-            $<$<COMPILE_LANGUAGE:CUDA>:--compiler-options;${FORTRAN_CONVENTION}>
-        )
+        if(NOT CMAKE_CUDA_COMPILER_ID STREQUAL "Clang")
+          target_compile_options(magma_nvcc_flags
+              INTERFACE
+              $<$<COMPILE_LANGUAGE:CUDA>:--compiler-options;${FORTRAN_CONVENTION}>
+          )
+        else()
+          target_compile_options(magma_nvcc_flags
+              INTERFACE
+              $<$<COMPILE_LANGUAGE:CUDA>:${FORTRAN_CONVENTION}>
+          )
+        endif()
     endif(COMPILER_SUPPORTS_FPIC)
 
     set(MAGMA_HAVE_CUDA "1")
diff --git a/control/magma_internal.h b/control/magma_internal.h
index 2310659235..c4d0eb8f6b 100644
--- a/control/magma_internal.h
+++ b/control/magma_internal.h
@@ -33,7 +33,7 @@
     // functions where Microsoft fails to provide C99 standard
     // (only with Microsoft, not with nvcc on Windows)
     // in both magma_internal.h and testings.h
-    #ifndef __NVCC__
+    #if !defined(__NVCC__) && !defined(__clang__)
 
         #include <float.h>
         #define copysign(x,y) _copysign(x,y)
@@ -42,7 +42,9 @@
         #define isfinite(x)   _finite(x)
         // note _snprintf has slightly different semantics than snprintf
         #define snprintf _snprintf
-
+    #elif !defined(__NVCC__)
+        // make sure this actually uses the C version and not the C++ overloads
+        #define copysign(x,y) copysign((double)x,(double)y)
     #endif
 
 #else