diff --git a/src/scheme/mod.rs b/src/scheme/mod.rs
index bdadbf04f1..ceab9aaea7 100644
--- a/src/scheme/mod.rs
+++ b/src/scheme/mod.rs
@@ -551,7 +551,9 @@ pub trait KernelScheme: Send + Sync + 'static {
         stored_flags: u32,
         token: &mut CleanLockToken,
     ) -> Result<usize> {
-        if offset != u64::MAX {
+        // u64::MAX = explicit stream write; 0 = non-positioned write from sys_write/sys_read.
+        // Any other offset would imply seeking on a non-seekable scheme.
+        if offset != u64::MAX && offset != 0 {
             return Err(Error::new(ESPIPE));
         }
         self.kwrite(id, buf, flags, stored_flags, token)
@@ -565,7 +567,7 @@ pub trait KernelScheme: Send + Sync + 'static {
         stored_flags: u32,
         token: &mut CleanLockToken,
     ) -> Result<usize> {
-        if offset != u64::MAX {
+        if offset != u64::MAX && offset != 0 {
             return Err(Error::new(ESPIPE));
         }
         self.kread(id, buf, flags, stored_flags, token)
diff --git a/src/syscall/fs.rs b/src/syscall/fs.rs
index f1080fdd37..63bfe87508 100644
--- a/src/syscall/fs.rs
+++ b/src/syscall/fs.rs
@@ -832,7 +832,7 @@ pub fn sys_read(fd: FileHandle, buf: UserSliceWo, token: &mut CleanLockToken) ->
             let offset = if desc.internal_flags.contains(InternalFlags::POSITIONED) {
                 desc.offset
             } else {
-                u64::MAX
+                0
             };
             Ok((
                 scheme.kreadoff(desc.number, buf, offset, desc.flags, desc.flags, token)?,
@@ -861,7 +861,7 @@ pub fn sys_write(fd: FileHandle, buf: UserSliceRo, token: &mut CleanLockToken) -
             let offset = if desc.internal_flags.contains(InternalFlags::POSITIONED) {
                 desc.offset
             } else {
-                u64::MAX
+                0
             };
             Ok((
                 scheme.kwriteoff(desc.number, buf, offset, desc.flags, desc.flags, token)?,