diff --git a/src/C_routines.c b/src/C_routines.c
index 37364543d..26d704974 100644
--- a/src/C_routines.c
+++ b/src/C_routines.c
@@ -86,7 +86,7 @@ void inflate_c(const uLong *s_deflated, const uLong *s_inflated, const Byte defl
 }
 
 #ifdef FYAML
-void to_flow_c(char **flow, int* length_flow, const char *mixed){
+void to_flow_c(char **flow, long* length_flow, const char *mixed){
   struct fy_document *fyd = NULL;
   enum fy_emitter_cfg_flags emit_flags = FYECF_MODE_FLOW_ONELINE | FYECF_STRIP_LABELS | FYECF_STRIP_TAGS |FYECF_STRIP_DOC;
 
@@ -102,7 +102,7 @@ void to_flow_c(char **flow, int* length_flow, const char *mixed){
   }
 
   *flow = fy_emit_document_to_string(fyd,emit_flags);
-  *length_flow = strlen(*flow);
+  *length_flow = (long) strlen(*flow);
 
   fy_document_destroy(fyd);
 }
diff --git a/src/YAML_parse.f90 b/src/YAML_parse.f90
index b1f5aaf71..cd79fe713 100644
--- a/src/YAML_parse.f90
+++ b/src/YAML_parse.f90
@@ -24,11 +24,11 @@ module YAML_parse
   interface
 
     subroutine to_flow_C(flow,length_flow,mixed) bind(C)
-      use, intrinsic :: ISO_C_Binding, only: C_INT, C_CHAR, C_PTR
+      use, intrinsic :: ISO_C_Binding, only: C_LONG, C_CHAR, C_PTR
       implicit none(type,external)
 
       type(C_PTR), intent(out) :: flow
-      integer(C_INT), intent(out) :: length_flow
+      integer(C_LONG), intent(out) :: length_flow
       character(kind=C_CHAR), dimension(*), intent(in) :: mixed
     end subroutine to_flow_C
 
@@ -216,7 +216,7 @@ function to_flow(mixed) result(flow)
   character(:,C_CHAR), allocatable :: flow
 
   type(C_PTR) :: str_ptr
-  integer(C_INT) :: strlen
+  integer(C_LONG) :: strlen
 
 
   call to_flow_C(str_ptr,strlen,f_c_string(mixed))
@@ -226,7 +226,7 @@ function to_flow(mixed) result(flow)
   block
     character(len=strlen,kind=c_char), pointer :: s
     call c_f_pointer(str_ptr,s)
-    flow = s(:len(s)-1)
+    flow = s(:len(s,pI64)-1_pI64)
   end block
 
   call free_C(str_ptr)